hmm... Not entirely sure.
Go into Bios (pres del usually at bootup)
Go into the first one I think it is usually, and find where it says 1st boot device, 2nd boot device etc.
On 1st boot device, this is obviously set to cd rom to read the windows disc. Make sure the 2nd boot device is set to the hard drive...
Then just save and exit
I dont' know if this is what may be causing it, but it's worth a try
*KaGe*