Windows XP will not reboot in safe mode

Approximately two weeks ago my sons laptop HP Nc 6220 was infected by the XP antivirus virus, before I found your website. I downloaded Revo uninstaller and it seemed to remove all of the traces of the virus. The computer was working again and I decided to run the updates from the Microsoft web site, but to my surprise and dismay; I found that his computer would not let him receive updates and it had been disabled. I followed the instructions for enabling them, but it wouldn't work. I worked with it for some time, before letting him start using it again (he started to get the "shakes" from not playing WOW). I loaded the militaries version of symantec and Mcafee ( I am in the US Air Force) and ran the scan of his computer and everything checked out OK. Two days ago the symantec software indicated that it had removed a virus and the laptop needed to be rebooted, since then his laptop will not get passed the "Windows" screen, before it starts the rebooting process. When it comes up with the black screen with all of the reboot options, no matter which one I choose (even safe mode) it does the exact same thing and reverts bak to the reboot options after a few minutes of running the windows screen. I do not have a copy of XP on disc and I am really hoping I do not have to buy one, but if that is the sollution please let me know. All and any help would be greatly appreciated. Thanks for you time and knowledge.