this doesn't happen to me and i've just reinstalled iPC on this machine several times the last few days playing with stuff. i'm using iPC 10.5.6 beta. i've updated to security update 2009-1, running voodoo kernel 2/9.6... i'm typing this on safari 3, and will update to safari 4.

i don't know why yours doesn't work though. but crashing webkit i've encountered on a real mac. i just reinstalled webkit and boom, all good.

maybe safe mode will work for you?