At the 75% in the installer it is busy modifying registry settings and copying files. It's a bit difficult to predict exactly which files and registry keys it are - but one which might be restricted on your current login is detailed in the subsequent URL.
http://support.microsoft.com/default.aspx?scid=kb;en-us;158909
Also check that you have full access to HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\Current Version and all it's subkeys. There are some entries it needs to create for help files, system settings, etc.
Then, make sure that you have full access to the folder you are installing WinGate to (Including the ability to create subdirectories). I don't think this will be the problem area as it should have failed a lot earlier then, but it might be worth a double check.
Then, if you've checked all of these and it still fails, would it be possible for you to copy the directory (In terms of filenames, etc.) BEFORE cancelling the setup at that point. (Perhaps even a snapshot of the Qbik Registry key at that point)
You can do that by opening a command prompt. Switch to the folder you were installing WinGate to and type:
dir /s > files.txt
That will create a file called files.txt in the folder, which you can then email to me. That will help track down the exact point, because I can then see exactly where it has gotten to in the installation.
