I installed XP Windows on my Laptop.It was working well.Today,I installed Windows Vista Upgrade that I had already installed on my Home Computer.It includes icons,wallpapers and desktop changes.I rebooted my Laptop after the installation and it started but just when the desktop was going to appear,an error came that the windows is closing Windows Explorer.The computer didn't started but just stopped.I turned off and again started it but it didn't worked.I have tried everyhting I can do,opening Windows Safely,Normally e.t.c but it doesn't start.Please tell me how I can make my Laptop work well like before?How do I put the XP again?