windows 98 start up will not load desktop/error loading explorer.exe/mcafee detects virus

My computer will go in start up and get as far as loading the background but no programs. When I do ctrl /alt /del there are no programs listed.

 

I get the error message: Error loading Explorer.exe You must re-install Windows.

 

Then I get another message: McAfee VirusShield has detected a virus on your computer. We recommend you do a virus scan...

 

Then the computer turns off.

 

I did re-install Windows 98. Same problem. Actually before I re-installed Windows it was not automatically giving me those error messages.

I cannot run a virus scan because I cannot get to the programs menu to run the scan.

I have McAfee through AOL so I do not have a disk to run a virus scan off a disk.

I can get in safe mode but no programs load there either.

 

HELP. I need step by step instructions because I am not very computer savvy.