So while struggling to get the sound working on my friends' little demonic HP 6630, he accidentally reset everything in the bios (he says it was an accident anyways, since I told him to never mess around with those settings). This caused some things to become uninstalled (ports, usb drives etc.) and really there wasn't anything I could do since I wasn't familiar with the default settings. I suggested maybe reformatting and installing from a generic windows 98 CD because as it was I had that in mind as a last resort for his lack of sound.

We did that but when the format was done and we started it up to reinstall the OS, the message 'Invalid system disk. Please replace the disk and press any key' appeared on a black Dos screen. No disk was in there yet, and pressing any key causes the message to come up again - doing anything causes it to come up. Inserting the win 98 disk makes no difference.

So, we're left with no OS installed and a system that insists a disk is in there that shoulnd't be even though there is none. It struck me that maybe it was talking about the hard disk and I remember giving the disk a name (and probably a new name) when the format was finished and it prompted for one but I'm not sure if this is the cause. I tried going into the Bios again but there is nothing really that stands out to me as a quick fix. Anyone have any idea what can be done here?

So you checked the boot sequence? Set it to CD ROM first and put the win 98 CD in.

Also, in this day of massively cd driven materials, sometimes someone will put a floppy in the disc drive, and forget about it?

Fixed it, just had to enable boot up scanning, lol. Thank you for the replies guys!