Here is what I did:
1.I installed it.
2.I then uninstalled dark basic pro because I was having problems with it and blitz terrain because it was too out of date.
3. I then re-installed dark basic pro (newest version) and all add-ons I own - this all worked fine.
4. Blitz terrain I went to uninstall so i could install it into the new version I downloaded.
5. Went through the progress of uninstalling and then it still says it still installed
6. I tired to install it anyway but it just gives me the option to modify or uninstall - I have tried modify but that did nothing and there no files as far as I'm aware on my computer to do with blitz terrain except the installer.
http://img541.imageshack.us/img541/9082/gamebanner.jpg