something very strange is happening to me, and i have no idea why...

i run the setup.exe file and it copys over the setup support files
then it says that my system configuration is correct
then, where from what i understand it is supposed to ask what components i want to install, it just installs something itself. i dont get given any options whatsoever through the whole installation.
then when its finished, i go to verify that its installed - and its not. its in add/remove programs, but its not in services, and not in c:/program files/microsoft.. blah.. (apparently default folder)

has anyone ever had a similar problem, or know what could be happening? cos im stumped...