Sayaf,
Judging by the directory and files you posted, there are some files missing from your installation. Did you download the Instrument I/O Assistant installer from the web? Or did you install it from the Driver CD that came with your LabVIEW 7.0? I can try to reproduce the installation problem you are seeing here, but I need to know how you are installing IIOA.
I know you said you have already tried uninstalling/reinstalling everything, but I think you should try to do this again. If you have been using the downloaded IIOA installer, then I would try to get your hands on the LabVIEW 7.0 Driver CD that should have come with your LabVIEW 7.0, and use that instead.
-Tommy