Can you please go into about:support in the address bar in Firefox, and copy and paste everything there into this thread?

I have a mac and I have the slanted screen problem as well. If i click on the bottom of the screen it goes back to normal for a second and then resumes the slant. Does anyone know what to do about this, as in, should I uninstall and reinstall firefox?

Can you attach a screenshot?

• http://en.wikipedia.org/wiki/Screenshot
• https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem

Use a compressed image type like PNG or JPG to save the screenshot.

Try to disable hardware acceleration in Firefox.

• Firefox > Preferences > Advanced > General > Browsing: "Use hardware acceleration when available"
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

• https://hacks.mozilla.org/2010/09/hardware-acceleration/

For anyone experiencing this issue, can you try installing the test build of Firefox located a http://ftp.mozilla.org/pub/mozilla.org/firefox/try-builds/jdrew@mozilla.com-70969d7d8523/try-macosx64/ ? See if this fixes the issue.

Also, after testing that, you should update to Mac 10.6.8, it also fixes this issue. Is there a reason you aren't updated already?

I can't upgrade to Mac OS 10.6.8: I have an old MacBook Air, and upgrading would hang my machine :-(

Unfortunately, the latest nightly build does not fix this problem.

I had no other way than downgrade to Firefox 17.0 for the moment, but I'll have to move to another browser if this issue with Firefox is not fixed.

Upgrading to 10.6.8 shouldn't hang your computer, it's just security and bug fixes, so it's actually important to have that. Please try updating.

I already tried once, and I had to scratch my machine: It basically freezes one of the CPUs when some temperature sensors are above a very reasonable value.

I won't try a second time, sorry...

By the way, Nightly 21.0a1 (2013-01-22) seems to work fine :-)