Since the PC does not have internet, it is unlikely (but not impossible) there is a virus. Have you tried both, using the keyboard to cut and paste, i.e. Control+X to cut and Control+V to paste as well as the icons in the tool bar ? Suggest, first, click start, run and type in regedit. Click on file at top and export the registry to the desktop.
Click on Start, Run and type in scanreg /fix. Note the space between the 'g' and the '/'. Restart the computer after this completes.
Also, if you have access to a computer with internet access, go to http://support.microsoft.com/kb/221512/EN-US/
This site will instruct how to Manually Restore the Windows 98 Registry to a previous setting. Good Luck