User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b12pre) Gecko/20110218 Firefox/4.0b12pre Build Identifier: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b12pre) Gecko/20110218 Firefox/4.0b12pre Latest nightly, only on 64bit build. Reproducible: Always Steps to Reproduce: 1.open minfield 2... 3.

Does the issue still occur if you start Firefox in Safe Mode? http://support.mozilla.com/en-US/kb/Safe+Mode How about with a new, empty profile? http://support.mozilla.com/en-US/kb/Basic+Troubleshooting#Make_a_new_profile Please post the graphics section from about:support

Neither a new profile or safemode helps. graphics; Adapter DescriptionRadeon X1950 Pro Vendor ID1002Device ID7280 Adapter RAM Unknown Adapter Drivers atiumd64 atiumdag atiumdva atiumd6a atitmm64 Driver Version 8.593.100.0 Driver Date 2-10-2010 Direct2D Enabled Blocked on your graphics driver. Try updating your graphics driver to version 10.6 or newer. DirectWrite Enabled false (6.1.7600.16699, font cache n/a)WebGL Renderer(WebGL unavailable)GPU Accelerated Windows0/1 Not sure why it suggests 10.6, it's not available for my card. Should it really be required for d2d in the first place?

The older versions of drivers can cause issues with D2D. That is why it's blocked. It doesn't know what versions ATI still supports or not, so it just gives a blanket update message.

Well, 10.2 is the latest driver for dx9 cards and it's a perfectly capable driver.

Setting direct2d and acceleration to forced enables d2d but does not fix the bug.