First and forehand, I am running JB 4.2.2 AOKP on my AT&T Samsung Galaxy S3. I have the latest gapps package installed after every time I flash an update to my ROM.
For some reason though, whenever I try to update either Gmail or Play Music, I get the error "Package file was not signed correctly. Uninstall the previous copy of the app and try again."
I can't uninstall the apps because they are used as system apps, and the best I can do is disable them, but that still didn't let me update them. I'm sure it has something to do with the gapps package that I flashed, but why does it not give me the same error when I update Play Movies and Play Magazines?
I do not use Titanium Backup to back up any of my apps, so I saw that that was a problem for some other people. If however, there is another question that relates more to mine, I will be glad to go and check it out, but after my looking I did not find a solution to my specific problem. Thanks in advance!
EDIT: Here's the link to the gapps package that I installed as well as the exact ROM I am using.