I'm not exactly a newbie at computers but there is no forum for M$ xp.
I have a pc that has had a virus this was (as far as I know) now been sorted using MSE,Avg and Malwarebytes,the only problem I'm having is that it refuses to get any security updates from M$ stating that the site is down,well I have another XP machine that has just got it's updates with no problem and my question is can a virus block this and apart from a complete reformat and new XP is there any way to sort this out? Thanks for your time in advance...
Very unwise to run two AVs together. They generally search each other and lock the PC up. Just because you were lucky with the two running together at a given point doesn't mean that an update to one or both wont result in a lock up.
I suggest you uninstall one then try your updates.