something is wrong with my xp comp, seriously needed help* Options

[TYPiKALFEMME]

(I have a Sony Vaio 2003 computer*) Okay well I have this occuring problem, I had this same problem 5months ago back in June 2005; and I went to Best Buy-(the store I bought the comp.) for them to fix it since I had warranty and coverage on it if I ever did have something wrong with it. And it worked fine till now. The problem is, when i turn on the computer, it starts up like its suppose to and it then it goes to the window where it says-Windows XP with the little green bar moving. And usually after the windows xp screen, its suppose to go to the welcome window and then to the desktop. But no, it doesnt even go to the welcome window or the desktop. IT JUST STAYS AT THE XP part. It just keeps staying there and it never moves. And btw, my keyboard somehow doesnt work when this happens, you cant even turn on the caps, num, scroll keys to light up. Nothing. And so the other logical thing to do, is to press the power button on the PC, and turn it off. A few minutes later, turn it on again right? Well it doesnt work, its the same thing! Sometimes the screen will say, You have restarted and turn off your computer improperly; etc. Please choose either Safe mode, Safe mode with Command Prompt(sp?), Safe Mode with (i forgot), Last good configuration, or start windows manually(sp?). And I have tried Safe Mode to restore my comp. 3 times and it hasnt done anything, I tried the starting windows manually but it just stays at dumb windows xp part, and I have tried last good configuration and it does lead to the desktop sometimes* But most of the time it's like the start windows manually. --I have no idea what the hell is wrong, because I'm in high school still, and i need to do my work on the comp. I dont want to have to keep on doing this and not ever getting to my desktop. I have no virsues, adware, spyware that type of thing-i always scab each week. Plus I dont think thats problem anyways. I had having to restore it, I have NO IDEA wthell is going on. I went best buy today to see if they can fix it and guess what..? It WORKED FINE AND DANDY over there! Gees, i felt like a fool but when I come here, its fine, a couples of times and now its starting again..Anyone have any idea? PLEASE HELP!!

[*kryogenix*]

Warranty?