Granting Permissions isn't working, cannot install apps

[ScottishDuck]

For some reason, whenever an application needs permissions to do something (install a pkg, start an app that uses admin privelages, etc), I input the correct password and then... nothing happens.

This means I have to use the terminal to install pkg files, but in the case of other things, like Adobe Creative Suite, I'm screwed.

I've tried repairing permissions and reinstalling the 10.7.2 combo update, any ideas?