Laptops freezing after login
We've had a problem on our network over the last few weeks and I can't fathom what's causing it. A member of staff will log in to their laptop, the desktop will appear but the machine then freezes and has to be powered off to get going again. Sometimes the second time it'll be fine, others it'll take three or four attempts.
This seems to happen to some staff more than others (either that or they're the only ones that bother to tell me there's a problem...) - some with laptops only a few months old, others that are older I could understand. All laptops are running XP SP3 with Office 2010, servers run Server 2003 R2 standard. One server holds the staff emails and shared documents, the other holds profiles for staff and students.
Problems seem to be getting worse since we had some network upgrades - gigabit switches installed at various points in the school. I can't see why this would cause the issue to get worse, but it's the only thing that's changed recently. Nothing showing up in the server or laptop logs as far as I can tell, does anyone know what the problem may be?
Sorry that this is a bit vague, but school broke up on Friday and the last few weeks of term are so busy I haven't had much time to look at the problem.