Could be that it's not agreeing with theme manager.
If you want, you should be able to copy the .theme file over, rename the copy to .zip, open it up with WinZip or whatever, pull the pieces out and extract them to the appropriate places or install them (e.g. a .wba file) individually. After that you should be able to load the pieces individually with the appropriate programs (icon packager, windowblinds, etc).
I'm not sure what to think about the wb piece hosing up windowblinds though unless it's not getting extracted right by theme manager.