Un-addressed issue regarding deleting text messages

Help. I have an iPhone 3GS with the latest iOS 5 update. I made the mistake of having tweets sent as text messages to my iPhone. As you can imagine I have thousands and I want to delete them. When I try either by finger swiping, edit and choosing that thread or choosing clear all/clear conversation the iPhone goes into sort of a freeze mode for 3-4 minutes then it goes to just the little circle thing for a minute or so then it takes me to the unlock screen. I have already deleted 1,000 or so manually without helping. I want to get rid of them all without deleting any of my regular text threads.

 

Fix

It seems that iOS 6 has made it easy to delete large threads, it was no issue.