I have 4 Giga systems all running XP, 3 of which use RME hammerfalls and run fine with the performance tool, and the 4th currently is more or less an identical system but has an M-Audio Audiophile instead of an RME.
The Audiophile PC always hangs when I do a file->open from the performance tool. I've done a fresh XP install, no other software installed other than Giga and performance tool. I've ordered a 4th Hammerfall to replace the Audiophile so will post here in a couple of days if this solves the problem - could be some hardware/software incompatabilty but I haven't had alot of time to troubleshoot.
Ian