Little Snitch--which I have--
should give you the option to allow
MS-Messenger--which I also have--to communicate through whatever port it asks. If it is NOT doing that, check to make sure you did not inadvertently deny access to the internet.
Since you are new to Mac, I recommend looking up Pogue's books--
Missing Manual,
Switching to Mac--for great overviews of the OS.
Now, the usual way to repair permissions is to restart on your installation disk, run
Disk Utility, and repair permissions . . . which takes a long time in OS X 10.5.5.
However, I suspect you have not done any maintenance. So I would suggest you get the freeware
Onyx which will run the maintenance scripts including permission repair, or the shareware
Cocktail which will do the same thing, but you can grade the amount of maintenance. In fact, I would try checking the
Little Snitch rules, running
Onyx, and see if that solves the problem.
"Messenger for Mac 7"--interesting, mine is only 6.0.3 . . . guess I need to update!
--J.D.