Error Creating a New Folder

On a Win98SE PIII 550mHz box I get an Explorer error when I try to creat a new folder or file. For instance when I right click the desktop and click on new in the menu, I immediatly get the error. This happens which ever way I try to create the new folder (right click menu, Toolbar File, or in a save window). The only way I’ve been able to work around is either using a dos prompt or using another computer on the internal network with privilages.
The error is the grey window with “This program performed and illegal operation …
Details were: Explorer caused an invalid page fault in module SHD0C40l.dll at 017f:s001f4fs.

Thanks for any help.