Some tabs are not being restored

Question

I use the "Show windows and tabs from last time" option, but sometimes when I close Firefox, some tabs come back in blank (with the "New Tab" title) and lose their navigation history. This sometimes happens to sites that I've been using for days before restarting my laptop (so it's not a connection issue).
For some sites, I can recreate this consistently (http://www.mangareader.net/). I open the site in a new tab, and after it has loaded completely I restart Firefox; after opening back again that specific tab is blank. Some sites work, some others don't. I can't see any relation between them. It's not related to my internet connection, since I have tried in many different places.

Answer 1

Application Basics
Name: Firefox
Version: 33.0
User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:33.0) Gecko/20100101 Firefox/33.0
Multiprocess Windows: 0/1
Crash Reports for the Last 3 Days
All Crash Reports
Extensions
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Version: 2.6.4
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ID: {d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d}
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Enabled: true
ID: searchy@searchy
Name: PDF Viewer
Version: 1.0.277
Enabled: true
ID: [email protected]
Name: Spanish (Venezuela) spell check dictionary
Version: 1.1.17
Enabled: true
ID: [email protected]
Name: Turn Off the Lights
Version: 3.0.0.16
Enabled: true
ID: [email protected]
Name: X-notifier
Version: 3.4.7
Enabled: true
ID: {37fa1426-b82d-11db-8314-0800200c9a66}
Name: Firebug
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Enabled: false
ID: [email protected]
Name: Hola Better Internet
Version: 1.4.995
Enabled: false
ID: jid1-4P0kohSJxU1qGg@jetpack
Name: MEGA
Version: 2.0.192
Enabled: false
ID: [email protected]
Name: Web Developer
Version: 1.2.5
Enabled: false
ID: {c45c406e-ab73-11d8-be73-000a95be3b12}
Graphics
Device ID: 0x 126
GPU Accelerated Windows: 1/1 OpenGL (OMTC)
Vendor ID: 0x8086
WebGL Renderer: Intel Inc. -- Intel HD Graphics 3000 OpenGL Engine
windowLayerManagerRemote: true
AzureCanvasBackend: quartz
AzureContentBackend: quartz
AzureFallbackCanvasBackend: none
AzureSkiaAccelerated: 0
Important Modified Preferences
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.privatebrowsing.dont_prompt_on_enter: true
browser.search.log: true
browser.sessionstore.upgradeBackup.latestBuildID: 20141007073543
browser.startup.homepage: http://google.com.do/
browser.startup.homepage_override.buildID: 20141007073543
browser.startup.homepage_override.mstone: 33.0
browser.tabs.warnOnClose: false
browser.tabs.warnOnOpen: false
browser.urlbar.default.behavior: 2
dom.mozApps.used: true
dom.popup_allowed_events:
dom.w3c_touch_events.expose: false
extensions.lastAppVersion: 33.0
font.internaluseonly.changed: false
font.name.serif.x-western: Trebuchet MS
media.gmp-gmpopenh264.lastUpdate: 1412212364
media.gmp-gmpopenh264.version: 1.1
media.gmp-manager.lastCheck: 1413237807
network.cookie.prefsMigrated: true
places.database.lastMaintenance: 1413239638
places.history.expiration.transient_current_max_pages: 104858
plugin.importedState: true
plugin.state.java: 0
plugin.state.sharepointbrowserplugin: 0
plugins.notifyMissingFlash: false
print.print_bgcolor: false
print.print_bgimages: false
print.print_colorspace:
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print.print_unwriteable_margin_right: 25
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privacy.cpd.cookies: false
privacy.cpd.offlineApps: true
privacy.cpd.sessions: false
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privacy.sanitize.migrateFx3Prefs: true
privacy.sanitize.timeSpan: 2
security.warn_viewing_mixed: false
storage.vacuum.last.index: 1
storage.vacuum.last.places.sqlite: 1413131346
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: 3.17.1 Basic ECC
Version in use: 3.17.1 Basic ECC
NSSSMIME
Expected minimum version: 3.17.1 Basic ECC
Version in use: 3.17.1 Basic ECC
NSSSSL
Expected minimum version: 3.17.1 Basic ECC
Version in use: 3.17.1 Basic ECC
NSSUTIL
Expected minimum version: 3.17.1
Version in use: 3.17.1
Experimental Features
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