Disk permissions repair problem

On my new Mac Pro with 1.5.2 OSX whenever I do a disk permissions repair with disk utility it takes several minutes (quite longer than my MBP) and then it reports a series of messages saying
ACL found but not expected in library
ACL found but not expected in applications
ACL found but not expected in applications/utilities

It reports that the disk permissions have been repaired but the next time I run it it repeats the messages and keeps taking a longer time than I expect.

I am new to Macs, and my only other experience is with the MBP which runs 1.4.11 OSX. It does disk permissions repairs much quicker and has never reported anything similar, and after it does any disk permissions repairs, I don't see them mentioned the next time I run the utility.

Can anyone please advise on what may be the problem? What is this ACL it keeps referring to? Is this a Leopard bug or a setup problem on my new Mac Pro or something else?
What might be the solution?

Thanks a lot for any advice.

Thanks.
So, are they a problem? Can they cause computer problems? Can I manually delete them somewhere so that they don't keep getting the same messages?

Thanks a lot, guys. That puts my mind at rest.

ChrisA said:

There is really no need to run "repair permisions" unless you have a problem.

Click to expand...

I read in the forums that you should always do a repair disk permissions before and after doing any updates or program installs.
I ran it after updating the new Mac Pro to 1.5.2 and after installing FCP Studio 2.
Like I said, I'm new to Macs and just trying to avoid problems.