Error 1327 on Win2000

I’m using Windows 2000 with SP4. Suddenly I received a repeated problem: Some applications, not all, when I try to install (example Adobe Acrobat v6.0)I receive this error:
“Error 1327.Invalid Drive: G:\”
and installation terminates.
Though my pc doesnot have a fixed drive G, but I have to plugin some storage media in at least 2 of my PC’s USBs to Get a Drive G mapped on the PC, otherwise I can not install that application.