I'm running Nightly on a brand new MacBook Pro (10.7.4) and very often pages are not fully displayed (I see half images and sometimes even mangled layouts). A new profile shows the same issue. Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:17.0) Gecko/17.0 Firefox/17.0 At first I thought it was a problem with hardware acceleration, but disabling it didn't solve the problem. Then I realized that shift+reload fixes the problem and there are several loading errors in webconsole, so maybe it's cache related. I can exclude network problems (other Macs and PCs on the same network work fine), Safari on the same Mac loads pages without problems. Not sure if it matters but this system uses an after-market SSD disk (SanDisk Extreme) with Trim enabled.
Created attachment 644643 [details] Example (apple.com/mac) This is an example (see header images). cmd+R doesn't fix the problem, cmr+shift+R does
Probably caused by bug 767779 if it started with today's Nightly. We backed it out and re-built. Can you please check for updates manually and report back?
I've been using the updated version for several minutes and it works fine (with the previous version I couldn't browse 10 seconds without seeing broken images). I'll let you close this bug because I never know the proper status for this kind of situations ;-)
Bug 767779 was backed out.