This may be because you have UAC (User Access Control) is switched on by default in windows 7 which could prevent certain type of action like opening outlook.
Try this and see it the error goes away.
Click Start button and type "UAC" in the "search programs and files" area, you will get "Change User Account Control Settings"
Open UAC and lower the settings to "Never notify" and click "OK" button.
Restart your computer and try again.
Lowering your UAC settings is not a good options but atleast you will know what is the problem.