There is no 4.12.8 yet, I think you mean 4.12.3 perhaps.

The freezes link FOTH left above is for windows not OSX. Which version of LW are you using now that you uninstalled the new version?

If upgrading to pro, it's often best to delete your LW preferences folder whilst LW is closed, found here: /Users/your_username/Library/Preferences/LimeWire

It would be helpful to know which OSX version you're running so specific advice can be given.