Win.com error

I wanted to reinstall my Windows 98 2nd OS, and I thought I could do that by changing the boot order in the setup menu by pressing F2 during loading to boot from my CD-Rom.  When I did this, the error message, "Cannot find Win.com, unable to continue loading Windows" came up.  I set the boot values back to default and tried again, but the same error message came up.  Now I'm stuck with with this error message no matter what I do.