Finder stuck at "Preparing to copy.."
Every time I try to copy large files (more than 100GB) the small window which shows the copy progress continues showing "Preparing to copy..". It is not really stuck, and I can cancel it if I choose to, but it doesn't copy the file either. I tried copying my iPhoto Library when I discovered this issue. It also happens if I enter Time Machine and try to restore and older (local) copy of the library.
Does anyone know how to solve this problem?
I would really appreciate any kind of help.
(I'm using OS X 10.8.2.)
Mac Pro, OS X Mountain Lion (10.8.2)