Windows ME: Various HDD errors: virus?

I have a Windows ME system with the following symptoms: Scandisk always runs on startup, there are about 3gbs of data on the drive yet Explorer reports 19 (of a possible 20), Defrag gets a “defrag006: Errors on drive. Run Scandisk”, Scandisk (in Safe Mode, no screen saver), runs forever and reports no errors. Anyone know of a cause and, better yet, a fix (that does not involve reformattting and starting over!)?