Cut, Copy and Paste error

Hi, I have a problem at work with a stand alone PC. It is a PII 450mhz IBM IntelliStation running WinNT 4.0, service pack 6 with 192MB of RAM. All of a sudden, we are unable to copy files from folder to folder on the hard drive, to a floppy disk or vice versa. Tried doing Cut & Paste, Copy & Paste, Drag & Drop but nothing happens and no error displays neither. Funny thing it’s that I was able to copy files in command prompt. Anyone have any idea what might of cause this or how to fix it. Please help!!!