Looks like the installer problem is a widespread issue if you try to do anything other than the "Easy" default directory install.
There are potential workarounds being posted in some forums; here are two copy/pasted from another board:
First:
1) Run the installer once, with the
non-default folder you want to install to. The installer will say it was
interrupted.
2) Download the “Windows Install Clean Up” tool from Microsoft.
(http://support.microsoft.com/kb/290301
has an explanation/download link)
3) Start the installer again, but don’t
click past the first screen that pops up.
4) Run the “Windows Install Clean
Up” and remove “Ghostbusters: The Video Game”.(You could probably also clean
your registry however else you wanted at this point if you're savvy).
5)
Click next in the installer, and reinstall to the same location you picked
before. It should now install correctly to the folder you chose.
The main key is to start the
installer a second time, clean the registry with the Windows registry tool, and
then finish running the installer.
Second:
A bit of experimentation yielded an alternate method that doesn't need any registry fiddling:
custom install option to install GB wherever you want.
When
the installation finishes, immediately run the installer again, but do
the easy install to C: This install will be fast and only install 7
files.
Copy these 7 files and paste them into the folder you installed to the first time.
Run game and enjoy.
