I guess we all run into the problem of an endless scanning session provided by netbeans. I als run into this by using the new version 7.2.
You know that netbeans is doing something strange when your ide slows down while the load goes up. Especially when "top" displays a hugh amount of used memory, swap space and cpu time, you know it is time to say "good bye" to your opened files and use a kill to force your will.
But what to do after that? First you can try to delete the netbeans cache.