Since when this is happening?
the accept button is not working.
You will get the accept button enabled after you get the answer.
So please answer my questions,
since when this is happening?
while restarting press and tap F8 key, does it brings the advanced menu to the screen, if yes, choose safe mode.
Ok restart again with F8 tapping.
When advanced menu appears, choose safe mode, reply here for further instructions.
We need to repair the operating system.
Do you have the installation disc?
Very nice. Insert the disc in CDROM, reboot the pc and follow the instruction in this link to repair the system, it will resolve the issue: http://michaelstevenstech.com/XPrepairinstall.htm#RI
Let me know how it goes.