FYI I haven't heard from Stardock yet but I finally got it to install correctly - I installed Stardock Central, then downloaded and installed via that interface and it worked. Hope this does for you too!
I am getting the same error message as the OP. I emailed Stardock and am waiting for their help...I tried the link Kizikala posted above and also the file that the registration page sent me (yes I bought the product before trying it, doh!) - the file is called WindowBlinds603_enhanced.exe - same error with both installers. I'm running Windows XP Pro with sp2 and all available Microsoft updates, computer is not a member of a domain and my account is a member of the local administrators group. I e