after formating my hard disk for fresh OS installation, when i start the machine it comes up with error message saying:

invalid system disk, replace the disk and press any key

i tried many options on BIOS but still this problem continues, the funny thing is that when i physically remove the cd drive this problem stops, but immediately i add it, this error message continues.
another funny thing is that this cd drive was working perfectly on the previous os (Win2000)
i'm simply stucked 'cos i need the cd drive to do the os installation
what could be wrong and how do go about this?
could it be that when i formated the hard disk that i did cleared some needed settings or what?
this machine is ibm (thinkpad type 2655) notebook pc

Did you burn the install CD properly? You have to "Burn Disc from iso Image" (or similar). If you see a single *.iso when you look at the CD in a file manager, you burned it incorrectly.