all my browser windows keep freezing

my brother installed a new harddrive yesterday and put my old one in as a slave harddrive. he reinstalled XP Pro. NOw alot of my windows are freezing all the time, does anyone have any clues as to why this might be happening?

What kind of computer is it?

Before he put it in did he turn off any & all Bios boot protections?

its a homemade computer. Athlon 1200, 256 MB DDR Ram, XP Pro.

I dont think its any of that stuff though because this never happened before he put in a new harddrive.

Thats the point, the bios thinks that the old HD is still there if you didn’t turn off the protections, so it’s using the boot sectors it created for it.