This problems seems to occur with Windows XP SP2. At the moment I don't think you can fix it yourself. We will try to fix it and make a new download available. We will probably have to use another installation program.
I will post a message here as soon as the fixed download is available...
I just created a new setup for Plugin Commander. I sent it for testing to a few people. If there is no problem, I will make it available for download soon.
If anyone wants to test it, too, please let me know.