No drag and drop on the desk top.

This is an NT machine. 4.0 with SP 5. Office 97 and IE 5.0 with SP 1. No virus can be found with anti virus software. Antivirus was updated 9/11/00. I am not able to drag and drop on the desktop at all. I can click a doc but cannot paste. I have uninstalled IE 4.0 and replaced with IE 5.0 SP 1, reinstalled mouse drivers. Power supply is good. Mouse works fine on other machines. Very strange. Please help.