Vista - Insufficient Privileges

I've been trying to open an application with a self-extracting installer I've downloaded, and keep getting this error message:

"Unable to write to the temp directory in C:\Users\X\AppData\Local\Temp\. Check that you have write access to this directory."

Every account has full access and ownership of every file on my computer, and the account I'm using is the admin. I've checked this more times than I care to count, have tried opening in safe mode to receive the same error message, and have even tried downloading a different version to see if maybe it was corrupt, and received the same result. I've had this error a few times in the past, but never on anything I was so intent on trying out that I've become this frustrated. Any ideas?

You do realize in Vista that the Appdata folder is not a real folder right? Thats why you cant write to it. its a "junction" Point- a shortcut. If you are using an older app, that looks for folders to install in that are no longer there (e.g., "my Documents"), the junction point shortcut will cause the install to fail.

http://www.svrops.com/svrops/articles/jpoints.htm

It extracts there by default. Is there any way through Vista functions that I can reroute the extraction? The application is encrypted, and I'm nowhere near experienced enough with that stuff to begin to mess with it.

Are you trying to use an XP app? try compatability mode to install.

Tried as well, still no dice. I appreciate your help, but I think I'm going to try a different application similar to this. Thanks!