Use your Windows Start-Up BOOTDISKETTE
From the DOS prompt run:
A:\>scandisk /all
... and then:
A:\>scandisk /all /surface [takes one hour per 10Gb of disk space]
... and then:
A:\>scanreg /fix , to repair the registry.
Try re-booting to safe mode and see if you can run defrag and your anti-virus scanner.
Try re-booting to the desktop.
This is the defrag from XP which is MUCH faster and does a MUCH better job on '98/ME
too!!!
XP DEFRAG FOR 98/ME DIRECT DOWNLOAD