Bad idea to turn off UAC.
I don't know if many people know, but if an application is installed with UAC on, then the application must be run with UAC turned on.
I try to avoid using technical language where possible, but it is needed here to explain the problem. (Strangely enough, I was reading about that in a computer magazine not too long ago)
The technical bit
Scenario 1: When UAC is turned on
When UAC is turned on, Windows uses a hidden folder at C:/Users/<username>/AppData/Local/VirtualStore/ to store the information (which is why you get the UAC prompt and the requirement to run as admin), and as a result, some data gets redirected to that folder (so if a program is writing to C:/Program Files/test, it would actually be redirected to C:/Users/<username>/AppData/Local/VirtualStore/Program Files/test.
Also, a similar thing happens in the registry, because Windows treats all accounts as standard accounts, and the UAC prompt is basically so a user can request elevated rights to access the VirtualStore data and the registry.
Scenario 2: When UAC is turned off
When UAC is turned off, Windows no longer uses the VirtualStore folder, which basically means that anything that was created before turning off UAC the program will not be able to find, as instead of looking in VirtualStore, it will be looking in it's actual folder - where it will not be able to find the information. Also, it writes to the registry differently.
Solution: You will need to re-install any programs that were installed whilst UAC was on in order to use them when UAC is turned off.
Shane