Problems with loading XP

Hello everyone,
I stumbled across some serious problem – I cannot turn my XP on. Why? After the screen with XP logo and this blue strip (loading) shows up, it stays on forever and the screen with my accounts doesn’t come next. I can only use safemode, that’s all. I scanned hard drives, I used hijack and so on – and nothing. My only assumption is that this may have something in common with iTunes software I downloaded just before this crash (it was iTunes update and Safari I guess which I cannot delete in safemode actually).
Please, help,
thank you.