Hmmmmm,

I loaded FF 3.5.1 on an XP SP3 box................it took ages to start up the first time. I tried a variety of tweaks suggested on the net but had no joy.

I then upgraded to 3.5.2, and the damn thing wouldn't even start.......... I am not a patient man and 15 minutes was long enough to ditch it. Not only wouldn't it work but it killed IE8 and K-Meleon at the same time! Funnily enough Opera 9.64 was immune to this and continued to work normally.