Opening files doesn't work no matter how many times I press the button.

Question

Application Basics
Name: Firefox
Version: 31.0
User Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:31.0) Gecko/20100101 Firefox/31.0
Crash Reports for the Last 3 Days
All Crash Reports
Extensions
Name: Adblock Plus
Version: 2.6.4
Enabled: true
ID: {d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d}
Name: Battlefield Play4Free
Version: 1.0.96.0
Enabled: true
ID: [email protected]
Name: Bitdefender Wallet
Version: 2.0
Enabled: true
ID: [email protected]
Name: Copy As Plain Text
Version: 1.0.9
Enabled: true
ID: {1a5dabbd-0e74-41da-b532-a364bb552cab}
Name: DownThemAll!
Version: 2.0.17
Enabled: true
ID: {DDC359D1-844A-42a7-9AA1-88A850A938A8}
Name: Extended Statusbar
Version: 1.5.10
Enabled: true
ID: {daf44bf7-a45e-4450-979c-91cf07434c3d}
Name: FastestFox
Version: 5.2.1
Enabled: true
ID: [email protected]
Name: Freemake Video Downloader Plugin
Version: 1.0.0
Enabled: true
ID: [email protected]
Name: Freemake Youtube Download Button
Version: 1.0.0
Enabled: true
ID: [email protected]
Name: Greasemonkey
Version: 2.1
Enabled: true
ID: {e4a8a97b-f2ed-450b-b12d-ee082ba24781}
Name: InstantFox
Version: 2.8.9
Enabled: true
ID: searchy@searchy
Name: Multifox
Version: 2.2.0
Enabled: true
ID: multifox@hultmann
Name: Online Convert
Version: 1.4
Enabled: true
ID: [email protected]
Name: ProxMate - Proxy on steroids!
Version: 2.3.3
Enabled: true
ID: jid1-QpHD8URtZWJC2A@jetpack
Name: Show my Password
Version: 2.0
Enabled: true
ID: {cd617372-6743-4ee4-bac4-fbf60f35719e}
Name: Skype Click to Call
Version: 7.3.16540.9015
Enabled: true
ID: {82AF8DCA-6DE9-405D-BD5E-43525BDAD38A}
Name: Strict Pop-up Blocker
Version: 0.2
Enabled: true
ID: jid1-P34HaABBBpOerQ@jetpack
Name: Tab Badge
Version: 1.15
Enabled: true
ID: [email protected]
Name: Text to Voice
Version: 1.10
Enabled: true
ID: [email protected]
Name: Tile Tabs
Version: 11.9
Enabled: true
ID: tiletabs@DW-dev
Name: URL Fixer
Version: 4.1
Enabled: true
ID: {0fa2149e-bb2c-4ac2-a8d3-479599819475}
Name: Video Resumer
Version: 1.1.3
Enabled: true
ID: videoresumer@jetpack
Name: Yamli for Firefox
Version: 1.1.0
Enabled: true
ID: [email protected]
Name: Webexp Enhanced
Version: 1.1
Enabled: false
ID: [email protected]
Graphics
Adapter Description: Intel(R) HD Graphics 4600
Adapter Description (GPU #2): NVIDIA GeForce GTX 760M
Adapter Drivers: igdumdim64 igd10iumd64 igd10iumd64 igdumdim32 igd10iumd32 igd10iumd32
Adapter Drivers (GPU #2): nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um
Adapter RAM: Unknown
Adapter RAM (GPU #2): 2048
Device ID: 0x0416
Device ID (GPU #2): 0x11e3
Direct2D Enabled: true
DirectWrite Enabled: true (6.3.9600.17111)
Driver Date: 1-22-2014
Driver Date (GPU #2): 9-1-2013
Driver Version: 10.18.10.3412
Driver Version (GPU #2): 9.18.13.2702
GPU #2 Active: false
GPU Accelerated Windows: 1/1 Direct3D 10
Vendor ID: 0x8086
Vendor ID (GPU #2): 0x10de
WebGL Renderer: Google Inc. -- ANGLE (Intel(R) HD Graphics 4600 Direct3D9Ex vs_3_0 ps_3_0)
windowLayerManagerRemote: false
AzureCanvasBackend: direct2d
AzureContentBackend: direct2d
AzureFallbackCanvasBackend: cairo
AzureSkiaAccelerated: 0
Important Modified Preferences
accessibility.newtabplus.homepage: chrome://branding/locale/browserconfig.properties
accessibility.newtabplus.page: 1
accessibility.newtabplus.ver: 4.5.2
accessibility.typeaheadfind.flashBar: 0
browser.cache.disk.capacity: 358400
browser.cache.disk.smart_size_cached_value: 358400
browser.cache.disk.smart_size.first_run: false
browser.cache.disk.smart_size.use_old_max: false
browser.cache.frecency_experiment: 1
browser.places.smartBookmarksVersion: 7
browser.sessionstore.upgradeBackup.latestBuildID: 20140716183446
browser.startup.homepage_override.buildID: 20140716183446
browser.startup.homepage_override.mstone: 31.0
browser.tabs.warnOnClose: false
dom.mozApps.used: true
dom.popup_allowed_events:
extensions.lastAppVersion: 31.0
font.internaluseonly.changed: true
gfx.direct3d.last_used_feature_level_idx: 0
network.cookie.prefsMigrated: true
places.database.lastMaintenance: 1406922206
places.history.expiration.transient_current_max_pages: 104858
plugin.disable_full_page_plugin_for_types: application/pdf
plugin.importedState: true
plugin.state.npuplaypc: 0
print.printer_Microsoft_XPS_Document_Writer.print_bgcolor: false
print.printer_Microsoft_XPS_Document_Writer.print_bgimages: false
print.printer_Microsoft_XPS_Document_Writer.print_colorspace:
print.printer_Microsoft_XPS_Document_Writer.print_command:
print.printer_Microsoft_XPS_Document_Writer.print_downloadfonts: false
print.printer_Microsoft_XPS_Document_Writer.print_duplex: -854238192
print.printer_Microsoft_XPS_Document_Writer.print_edge_bottom: 0
print.printer_Microsoft_XPS_Document_Writer.print_edge_left: 0
print.printer_Microsoft_XPS_Document_Writer.print_edge_right: 0
print.printer_Microsoft_XPS_Document_Writer.print_edge_top: 0
print.printer_Microsoft_XPS_Document_Writer.print_evenpages: true
print.printer_Microsoft_XPS_Document_Writer.print_footercenter:
print.printer_Microsoft_XPS_Document_Writer.print_footerleft: &PT
print.printer_Microsoft_XPS_Document_Writer.print_footerright: &D
print.printer_Microsoft_XPS_Document_Writer.print_headercenter:
print.printer_Microsoft_XPS_Document_Writer.print_headerleft: &T
print.printer_Microsoft_XPS_Document_Writer.print_headerright: &U
print.printer_Microsoft_XPS_Document_Writer.print_in_color: true
print.printer_Microsoft_XPS_Document_Writer.print_margin_bottom: 0.5
print.printer_Microsoft_XPS_Document_Writer.print_margin_left: 0.5
print.printer_Microsoft_XPS_Document_Writer.print_margin_right: 0.5
print.printer_Microsoft_XPS_Document_Writer.print_margin_top: 0.5
print.printer_Microsoft_XPS_Document_Writer.print_oddpages: true
print.printer_Microsoft_XPS_Document_Writer.print_orientation: 0
print.printer_Microsoft_XPS_Document_Writer.print_page_delay: 50
print.printer_Microsoft_XPS_Document_Writer.print_paper_data: 1
print.printer_Microsoft_XPS_Document_Writer.print_paper_height: 11.00
print.printer_Microsoft_XPS_Document_Writer.print_paper_name:
print.printer_Microsoft_XPS_Document_Writer.print_paper_size_type: 0
print.printer_Microsoft_XPS_Document_Writer.print_paper_size_unit: 0
print.printer_Microsoft_XPS_Document_Writer.print_paper_width: 8.50
print.printer_Microsoft_XPS_Document_Writer.print_plex_name:
print.printer_Microsoft_XPS_Document_Writer.print_resolution: 0
print.printer_Microsoft_XPS_Document_Writer.print_resolution_name:
print.printer_Microsoft_XPS_Document_Writer.print_reversed: false
print.printer_Microsoft_XPS_Document_Writer.print_scaling: 1.00
print.printer_Microsoft_XPS_Document_Writer.print_shrink_to_fit: true
print.printer_Microsoft_XPS_Document_Writer.print_to_file: false
print.printer_Microsoft_XPS_Document_Writer.print_unwriteable_margin_bottom: 0
print.printer_Microsoft_XPS_Document_Writer.print_unwriteable_margin_left: 0
print.printer_Microsoft_XPS_Document_Writer.print_unwriteable_margin_right: 0
print.printer_Microsoft_XPS_Document_Writer.print_unwriteable_margin_top: 0
privacy.sanitize.migrateFx3Prefs: true
storage.vacuum.last.index: 1
storage.vacuum.last.places.sqlite: 1406135669
JavaScript
Incremental GC: true
Accessibility
Activated: false
Prevent Accessibility: 0
Library Versions
NSPR
Expected minimum version: 4.10.6
Version in use: 4.10.6
NSS
Expected minimum version: 3.16.2 Basic ECC
Version in use: 3.16.2 Basic ECC
NSSSMIME
Expected minimum version: 3.16.2 Basic ECC
Version in use: 3.16.2 Basic ECC
NSSSSL
Expected minimum version: 3.16.2 Basic ECC
Version in use: 3.16.2 Basic ECC
NSSUTIL
Expected minimum version: 3.16.2
Version in use: 3.16.2
Experimental Features
Hi. Whenever I want to upload a picture or a file, no matter how many times I press the "Upload" or "Browse" button, nothing happens. I can keep spam clicking on it and it wouldn't do anything. This is not specific to a site, but happens everywhere. Dragging and dropping files works on Facebook and Imgur, but not all websites support this. I'm using Firefox 31.0 on Windows 8.1. Yes, I have tried restarting Firefox and computer, this has been happening for a while now. Thanks.

Answer 1

Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen) as a test.
*http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/
This probably still applies to Windows 8:
Try to delete the MRU (Most Recently Used) ComDlg32 registry keys with the registry editor (regedit.exe).
Navigate to: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\ComDlg32
Delete the subkeys (LastVisitedPidlMRU and OpenSavePidlMRU)
Be cautious with editing the registry as there is no Undo possible: all changes are applied immediately.
You can export registry keys before making changes.
* http://www.winhelponline.com/articles/195/1/How-to-clear-the-file-names-MRU-in-Common-Dialog-boxes-in-Windows-Vista.html