I`ve downloaded Stencyl via Windows XP or other Computer System. The installation file seems to be another version. Then I copied this version on a usb-stick. At last I installed the installation program on my window vista pc.
After reading this, and having done pretty much all my Stencyl-ing on Vista thus far without problem (or I should say, without glitches, hehe), I can almost guarantee you I know what the problem is.
Are all of y'all downloading Stencyl (or any applicable extensions) using Internet Explorer or Firefox?
If so, don't unzip anything. Don't install anything. Right-click every file you download -before- doing either of these things, and click Properties->Unblock.
Now, right-click the installation file and choose 'Run as Admin', -not- just 'Run'.
What's happening is you're literally missing some files, that were supposed to be in your Stencyl folders, and were blocked/altered during installation, either because your system decided not to trust the download source, or because you didn't click 'Run as Admin'. And Vista is telling you that everything installed completely and correctly, when it didn't. It's especially frustrating because usually a program will still work... until it doesn't.