I had twixtreme on my phone, and deleted it. Not through the desktop manager, just through the delete function on the phone. I tried installing ubertwitter, but the error "cannot install. missing filenet_rim_bbapi_messagelist" comes up in the download screen. So I tried to reinstall the exact same version of twixtreme, and that error still comes up.
Did you restart your device after the uninstall? Usually it will tell you that you should restart.
So if you haven't done that yet I suggest doing a battery pull, not just holding the end call button. Hopefully when it gets all restarted you'll be able to install ubertwitter without issue
Posted from my CrackBerry at wapforums.crackberry.com