reinstalling parallels 3

WTF? I have an iMac running 10.4.11 and Parallels 3. I recently had a system melt-down and had to reinstall my OS. I'm now trying to reinstall my Parallels and keep getting hung up at the 21% mark. The computer churns and clicks and sounds like it's really trying to do something, but all I get is the message "there were errors installing the software" at the top of the installation screen and "please try installing again". I've tried uninstalling and am told there is no Parallels currently installed. I've repaired permissions, restarted the system and even swore at it, to no avail. It really is time to upgrade, but I don't want to go ahead until I know I can get what I have working.

Any ideas?