xp freezee’s after joing win2k domain

Ok here is anothe one i have several systems that freeze when you select the start button but unfreeze about 5 min later, everything on the desktop works fine, logon times are great and the start button does not lock up when the admin is logged on. i have no win2k domain polices on these users or computers(trying to fix the problem i removed them.. uninstalled sp1 and the security patch that slowed down things according to microsoft, also tried reformating and clean in stall still no luck. helpplease!