Well, you will need to wait for someone sharper than myself to respond. The only other thing that I can think of is to log in as administrator in Safe Mode and see what happens.
Can you right click teh installer<|>properties>details>who is the file owner?
If it is a download it can be configured to have trusted installer run it, and TI had even more rights than admin.
failing that where is the installer file located, desk top?, other drive? was it in another OS?