I had similar issue in 9.10 with the E220. I have the K3715 now and it works flawlessly in 10.04. I was connected for 6 hours the other day with no issues. Must be an issue with the E220. Bit worrying that they haven't fixed it in 6 months. Have you logged a bug on Launchpad?
6 months? It's been over a year. The problem started in 9.04. I had to switch back to 8.10 to get 3G.
I'm getting Ubuntu tomorrow finally (this silly uncapped shaping makes it too slow to download), can't wait to install.