Firefox & ATI9600XT crashes

Dear News-Group-Users,

I use the newest Firefox1.4 (English) with my (still good) Computer. 
Since I installed Firefox it crashes several times a day (it crashed 3 
times in 2 years before).

It's always while using (or closing) Firefox, a blue screen appears 
saying that ATI3diag.dll crashed. But installing older and 100% stable 
drivers didn't help, I expect the problem to come from firefox directly. 
Does anyone know this problem or perhaps have a solution. I would be 
very thankful!

Peter

p.s. the E-Mail-Address looks funny but works