Sounds like it just needs a rebuild. If you've still got your copy of xp there's a repair command you can use which replaces all the core components. Its your best bet without wiping it and startinv from scratch.
Doing very well Mr Luke cheers, completed Mass Effect yesterday after a marathon gaming sessions of 13/4 hours straight or something. Was pretty epic! Done a broadcast on Friday night with Paul on PreParty Radio, streaming webcam with it too, was a great laugh! You ever going to get back into the streaming business?