I am having problems with Windows XP at start-up. When switching on the computer goes through its regular pre windows programs, however once these have been completed the machine hangs up. I do not get as far as the white status bar and the Windows loading page. After switching off and on several times I might be lucky to access the Windows start-up and everything works reasonably well. Recently, my computer was infected by the ‘byteverify’, ‘exception exploit’ and ‘sobig’ viruses, however these were identified and removed by Norton anti-virus. The removal was confirmed by ‘cleaner’ which found no evidence of viruses. I am running Widows XP home edition with AMD Athlon XP1500+, 1.33Ghz and 512 MB RAM. Any advice is greatly received.