Try right-clicking on the installation executable and clicking "run as administrator". also while installing it, try changing its install path to "C:\program files\computerease\" if it isn't already.
If that still doesn't work, and you don't mind totally lowering your system security temporarly because this is a mission critical program and you trust it explicitly, you can go to
www.tweak-uac.com and download tweak uac. That has the power to disable the user account control on Vista which some older programs that sloppily want to copy, place, and change files anywhere they please on the OS drive have problems with.
If it still fails, answer that it installed correctly to the prompt. Go to the programs folder and try to open it from there. If the program won't run, your only hope is from the program vendor's website. They may have an update to the program that allows it to run on Vista.
If that doesn't work then you are more than likely out of luck for that particular program until the vendors make a new version of it.
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