Every website I try to go to (such as Facebook, Twitter, etc that are safe) is saying that the website is unsafe and that I must accept the certificate).

Question

Yesterday my Firefox seemed to spasm and I believe I had a virus (every time I hit the "home" button which is google.com for me, it would send me to this weird site that I knew wasn't safe). I uninstalled and re-installed Firefox and ran virus scanners but nothing was found. After restarting Firefox, every website that I try to go to is giving me an unsafe error and that I must give each site a security exception, even for safe sites like Facebook, Twitter, etc. Once I did get on Facebook, everything is in HTML format and I can't use it at all I tried restarting/uninstalling/resetting Firefox again but to no avail. I checked my Firewalls and nothing came up. Here is the data from the troubleshooting information.
<pre><nowiki>Application Basics
Name: Firefox
Version: 34.0
User Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:34.0) Gecko/20100101 Firefox/34.0
Multiprocess Windows: 0/1
Crash Reports for the Last 3 Days
All Crash Reports (including 3 pending crashes in the given time range)
Extensions
Name: avast! Online Security
Version: 9.0.2021.112
Enabled: false
ID: [email protected]
Graphics
Adapter Description: Intel(R) HD Graphics 4600
Adapter Description (GPU #2): NVIDIA GeForce GT 755M
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): 0x0fcd
Direct2D Enabled: true
DirectWrite Enabled: true (6.3.9600.17111)
Driver Date: 8-19-2013
Driver Date (GPU #2): 10-4-2013
Driver Version: 10.18.10.3277
Driver Version (GPU #2): 9.18.13.2745
GPU #2 Active: false
GPU Accelerated Windows: 1/1 Direct3D 11 (OMTC)
Subsys ID: 380117aa
Subsys ID (GPU #2): 380117aa
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: true
AzureCanvasBackend: direct2d
AzureContentBackend: direct2d
AzureFallbackCanvasBackend: cairo
AzureSkiaAccelerated: 0
Important Modified Preferences
browser.cache.disk.capacity: 358400
browser.cache.disk.smart_size.first_run: false
browser.cache.frecency_experiment: 3
browser.places.smartBookmarksVersion: 7
browser.sessionstore.upgradeBackup.latestBuildID: 20141120192249
browser.startup.homepage_override.buildID: 20141120192249
browser.startup.homepage_override.mstone: 34.0
dom.mozApps.used: true
extensions.lastAppVersion: 34.0
gfx.direct3d.last_used_feature_level_idx: 0
media.gmp-manager.lastCheck: 1417643038
network.cookie.prefsMigrated: true
places.history.expiration.transient_current_max_pages: 104858
plugin.disable_full_page_plugin_for_types: application/pdf
plugin.importedState: true
privacy.sanitize.migrateFx3Prefs: true
Important Locked Preferences
JavaScript
Incremental GC: true
Accessibility
Activated: false
Prevent Accessibility: 0
Library Versions
NSPR
Expected minimum version: 4.10.7
Version in use: 4.10.7
NSS
Expected minimum version: 3.17.2 Basic ECC
Version in use: 3.17.2 Basic ECC
NSSSMIME
Expected minimum version: 3.17.2 Basic ECC
Version in use: 3.17.2 Basic ECC
NSSSSL
Expected minimum version: 3.17.2 Basic ECC
Version in use: 3.17.2 Basic ECC
NSSUTIL
Expected minimum version: 3.17.2
Version in use: 3.17.2
Experimental Features
</nowiki></pre>
Hopefully you can figure something out as I love Firefox but it's very frustrating that I can't use it and that this is happening. I also use Avast! Anti-security but I'm fairly certain that is having no effect on this problem. As I said I've also ran malware and virus scanners but nothing came up harmful.

Answer 1

Hello,
Try disabling Avast's web shield and try going to a few safe sites where you experienced the "untrusted connection". You can also follow this article for other common troubleshooting steps: [["This Connection is Untrusted" error message appears - What to do]].
You can try these free programs to scan for malware, which work with your existing antivirus software:
* [http://www.malwarebytes.org/products/malwarebytes_free/ MalwareBytes' Anti-Malware]
* [http://general-changelog-team.fr/en/downloads/viewdownload/20-outils-de-xplode/2-adwcleaner AdwCleaner] (for more info, see this [http://www.bleepingcomputer.com/download/adwcleaner/ alternate AdwCleaner download page])
* [http://www.microsoft.com/security/scanner/default.aspx Microsoft Safety Scanner]
* [http://support.kaspersky.com/viruses/disinfection/5350 Anti-Rootkit Utility - TDSSKiller]
* [http://www.surfright.nl/en/hitmanpro/ Hitman Pro]
* [http://www.eset.com/us/online-scanner/ ESET Online Scanner]
If your home page is has been changed, and you don't have any suspicious extensions:
* Tools (or [[Image: New Fx Menu]]) > Add-ons > Extensions
You can use the [https://addons.mozilla.org/en-US/firefox/addon/searchreset/ Search Reset Tool] to reset your home page, new tab page, and search bar back to default. The extension then uninstalls itself once these preferences are reset.
Let us know if that helps.