It seems like the 4.33 setup is trying to uninstall/modify an existing 4.33 install. It is finding a registry entry but the registry entry points to a folder without 4.33 in it. I am guessing that you installed 4.33 before and had an incomplete removal, leaving behind the registry info.
The registry is both easy to edit but as potentially damaging as hitting the computer with a flaming sledgehammer. As long as one is awake there is no cause for fear in doing so.
Open the Windows registry editor which may be done by typing “regedit” into the start menu search or using the run command and running regedit. The registry is laid out in a folder and key format. The 4.33 registry information should be found in HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Benchmark Sims\Falcon BMS 4.33 (at least on Windows 7 x64). Deleting the folder “Falcon BMS 4.33” should allow you to attempt the install again fresh.