User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:13.0a1) Gecko/13.0a1 Firefox/13.0a1
Build ID: 20120218031156
Steps to reproduce:
Create a new tab.
Spaces for thumbnails for frequently accessed pages are displayed, but the thumbnails are not. All thumbnails appear as blank grey with page labels beneath them.
Thumbnails contain thumbnails of pages.
Do you have any preferences which delete your memory cache at shutdown? or do you use it at all? that would be bug 724408 if true.
Will be fixed with bug 744388.
Fixed by bug 744388.