Can't Adjust clips over :29

Hi!

So I'm editing to a piece of music, and as I'm trying to match the clip lengths to the beats, specifically going for :31, everything I input gets automatically changed to 1:00 or :29. Is it my imagination or is the program incapable of timing anything between :30-:59? The precision editor behaves in exactly the same way. Has anyone else experienced this problem? I tried making the clip longer but it didn't solve anything.

Thanks!!

edit: this post attached info about an old computer to this post for some reason- please disregard as I can't seem to remove it. Current machine is macbook pro, mavericks.