office won’t install but says successful

I’m trying to install Office 2000 Small Business SR-1. You run setup and put in the cd key, selecting customize or just the standard setup and it goes through the motions and looks like its going to install ok. Then right at the last minute, the progress bar goes backwards looking like its undoing settings and then you get a message saying “Office 2000 SB SR-1 completed successfully” but when you look the program is not installed. I’ve tried running the setup numerous times even after rebooting but no luck. I know the program is not there because .xls and .doc file extensions aren’t recognized.