"Invalid system disk..." message.

My computer has become completely
inoperable. It seems like a virus attacked it,
and my control panels were no longer
accessable. The computer was still
functioning, but when I downloaded a program
from the internet called Tune Up Utilities 2004,
things got worse. The program supposedly
helps to clean up your files and do a defrag.
When I restarted the computer I received a
message saying "Invalid system disk.
Replace the disk and then press any key".
Well, there was no disk in, and when I pressed
a key, the same message popped up again
and again. Have I totally destroyed my
computer? Is there a way to have this repaired
and still save a lot of the files I have on my
hard drive? If they have to go, so be it, but I
would prefer to save them if possible.
It's a Compaq Presario 2285V, with Windows 98.

Thanks.

Do you have any recovery disks or at least a bootable CD that can boot to DOS?

[glb]Gizmo73[/glb]

boot  to safe mode.........at the msdos prompt....type scanreg/restore......chose the last  good cab file<cab file started on xyz day>answer yes to the spalsh screen

you havent left a floppy disk in the drive have you?/

I am having the exact same problem. Have you had any luck fixing yours? I am about to pull my hair out. I've been told to set to boot from CD instead of C drive but I have no dos prompt just the same message ( Invalid system disk replace and press any key) over and over.
Help me if you can
Thanks
Missy

http://www.computerhope.com/issues/ch000229.htm

Set the first boot device to CD-ROM in the BIOS and reboot with CD present.