@Milkshanks It says a file is missing, so guiminer might have been installed into a folder with strict permissions, such as Program Files. He should try installing into a normal data folder, not a system folder.

On a side note, I'd appreciate if guiminer could be made to install in Program Files and the 'Programs and Features' Control Panel with a normal setup program, this is the only application I am running that does not conform to Windows requirements or guidelines.