Check how much free hard drive you have for virtual mem. I am using p4 2.8 1g and vmem set to initial 4096 to max4096 (Quik reminder: Start | Control Panel | System | Advanced | Settings btn under performance | Advanced tab | Virtual memory Change btn then set custom to 4096/4096 on a nice harddrive with free space). I have monitored my renders - and can guarantee you that a clean disk with lots of harddrive is very very important to keep the Render Firefly Production going [no lockup] - so assume that when you go to hair/mat/etc - it is grabbing harddisk with the texture/smooth shaded display on. Once a week I do a defrag on all drives on xppros from admin tools as they get well used by office and all 3d programs. Good Luck and by all means make sure you are running the sr2.1 at least (sr3 works on 98 laptop but been 2 chicken to try on XPpro)