Ahhh got it matey,have you tried starting up in updus Modus?
If this doesnt work,do you owe a XP software?
If so place in the harddrive let in run for while and then ESC it.
And then try starting up.
I had the same problme with my packard bell desktop ages ago,lastly after many failure attempts of runing it in updus Modus i allowed win 2000 (was the only software i head back then without an error) to run.
Upon ESCing it after 2 mins when i started up again,it worked.
So try that.