Try SAFE Boot & Repair Permissions I updated to QT 7 without thinking & had issues with another program (but not LW.) I ended up updating it & not only repairing permissions but also repairing disk with Disk Utility & Norton Utilities. Perhaps a couple of restarts also helped to sort it out.

If that doesn't work then try deleting LW's preferences whilst LW is closed. Make a note of your settings b/c you'll need to reset them. Prefs are found here: /Users/your_username/Library/Preferences/LimeWire