I had this problem with the same setup (WinXP and Windowblinds 7.x). I was able to eventually diagnose it to the Firefox option "Use hardware acceleration when available" which can be found under Tools>Options>Advanced. When I disabled this option I no longer had the problem. Conversely, re-enabling it caused the problem to return. There must be some kind of incompatibility within the hardware acceleration calls made by firefox to the display drivers. I hope you find this reply helpful and that it resolves your problem.

This seems to work. Thank you.

for me not solved my problem, I do not know if it was like your here is a page of my problem

https: / / support.mozilla.com/en-US/questions/795973

I too was experiencing a similar odd behavior with FF 4.0+ and WindowBlinds 7.2 on WinXP Pro. I initially tried the chosen solution (from jflorez) of disabling Firefox's "Use hardware acceleration when available" option, but this only seemed to work correctly for me half of the time. At this point, I began taking a closer look at WindowBlinds' options in attempts to fix the incompatibility, and fortunately, managed to find a solution.

As Firefox has it own skins (themes), WindowBlinds does not need to touch it at all; effectively, it should simply ignore the Firefox application altogether. This can be done by opening WindowBlinds and clicking the Settings button (near the top of the WindowBlinds 7 Configuration window). In the Settings window, select the Per application tab and click the Add... button. Browse to the X:\Program Files\Mozilla Firefox\ directory and choose the firefox.exe ejecutable and click OK. In the Per application settings window under Total exclusion, check the "Ignore this application and do not skin it" option and click OK.

Lastly, if Firefox is currently running, it will need to be restarted for the changes to take effect. In short, I sincerely hope this solution helps other Firefox users who are experiencing this problem.