windows 98 machines. If this can be moved....thanks

miknel

See if you can see the taskbar by moving the mouse pointer toward the place
in which it should be and right-click on an empty portion of it and select
Properties; if not, open the Control Panel in My Computer to set Taskbar
"Always On Top". Is the Task Bar above or below, or on the sides of the
screen?

Did you see a pop up on those machines saying spyware was found and asking if you want to remove it, prior to this happening?
What anti-virus program are you using on each machine?  we need to know to discover what is causing this rampant problem lately.

Follow the procedures here:
Blank Desktop or Illegal Operations Error Message After You Install Internet Explorer:
http://support.microsoft.com/?id=kb;en-us;249191

If those procedures do not help, have a look here:
Recovering From a Failed Internet Explorer Upgrade in Windows 98:
http://www.cs.bsu.edu/~gjjones/administrivia/stories/2003/03/21/recoveringFromAF
ailedInternetExplorerUpgradeInWindows98.html
or
http://tinyurl.com/r5ba

Especially this section at the end:

"If you still have boot problems after you reboot, you should use the command prompt to edit the c:\windows\system.ini file. On the command line type edit c:\windows\system.ini.

"Once it is open, change the line shell=explorer.exe to shell=progman.exe. What you are doing here is changing the default shell (that is having problems) from the Windows Explorer to the old Windows Program Manager shell.

"Reboot Windows. It should now successfully boot with no errors into an empty Program Manager shell. Use the File | Run | Browse drop down menu selection to browse to c:\program files\internet explorer and launch ie5setup.exe or ie6setup.exe (depending on what is there). Do a custom install and check all the Bold faced options. When the setup program alerts you that these files are already installed, tell it to reinstall all of the files.

"When the Internet Explorer Setup program is done and reboots, hit the F8 key to bring up a Boot Menu. Choose Command Prompt and boot to the command prompt. Once there, type edit c:\windows\system.ini and, once it is open, change the line shell=progman.exe back to shell=explorer.exe. Save and exit the file. You have now set the shell back to the original value."