It probably just has a string of code in that ROQS WU that doesn't run right on the AMD X6 rigs. I say this now, because I just called up my Bro, and we switched his rig from Prima to AQUA - and same exact thing - hard crashes just after Win7 boots (i.e. right when BOINC kicks in.)
He has a 1055T, I have 1100T. Anyone else have a similar rig to confirm the theory?