Broken Install

A client tried to install Symanted Desktop and did not complete the installation. Now everytime he turns the computer on it brings up an error message that c:\winnt\temp\instbin.exe cannot be found. HE HAS LEARNED TO USE CTL-ALT-DEL to bring up the task manager and kill that process and start a new one (explorer). This is how he gets into his computer now. I tried to delete all references to install but it did not fix the problem. Any suggestions short of installing the Symantec product and uninstalling it.