When i start up my computer it comes on but then before it actually starts up it says boot from ATAPI CD-ROM then says invalid system disk please replace the disk and press any key to continue!!! what do i do it's driving me crazy!!! I obviosly asked this ques from an other P.C

have you got a CD in the drive? if you have it may be trying to boot from it

Is the hard disk recognized properly in the system bios? Your POST screen should display this. We need to know if the system "sees" the disk at the hardware level.

What happens when you "press any key to continue"? Do you still get an invalid system disk error? If so, the boot files/path is not being found/seen.

Boot with your 98 EBD (Emergency Boot Disk) with CDROM support. When you get the A:\> prompt, put a "factory" data (not music) CD in the drive and try to get a directory listing. ie; dir/a x: (where x: is your assigned device letter.) If you get one, the hardware is OK and we can forget about that for now.

At the A:\> prompt, type in;

chkdsk c:

and hit enter. If there are any errors on the hard disk this should report them. It won't effect a repair if there are errors, but we'll come back to that later. What is the disk status?

Again at the A:\> prompt, type in;

dir/a c:

and hit enter. You should see your windows directory and various files in the root directory. Is io.sys, msdos.sys, and command.com there?