I figured it out, guys. What happened was:
1. During the first time I tried to upgrade packages, apper/yum installed the new ones but since the system froze, it did not uninstall the old ones.
2. Because of that, I got duplicated packages. For example, I had two versions of qt.
What I did:
1. Removed all the duplicated packages with package-cleanup --cleandupes;
2. Checked orphan packages with package-cleanup --orphans and removed SOME of them (be careful when you do this)
3. Removed manually some orphan packages (some old ones don't have a F17 version yet like veetle but they still work)
After I did that, I noticed that skype was not working. Trying to start it from terminal, I found out that there were some libraries missing. Using whatprovides, I got all the packages I need to get skype running again. Sweet!
I think I'm not a noob in linux anymore... =D