The login in is to allow you to use special backgrounds, send Handcent's version of Ecards etc. to other users of Handcent. I have used Handcent for while now and haven't had any issues, even after the recent updates. Before you try the following, go into your text messages and save any text you may want along with any pictures and videos you have sent or received. Once that is done, go to menu>applications>manage applications>Handcent>clear cache then clear data. This will erase all of your text messages from Handcent but not from the native messaging app ("Messaging" in your app drawer). If that doesn't work, try uninstalling Handcent then reinstall it. Don't forget about having the messaging app. If this problem persists, while you are trying to figure it out you can still send SMS/MMS through the native app. Just thought about this, you may want to delete all messages in your other message app as well once you have saved any info you want off of it. Good luck!
Almost forgot: The login field is under the menu from the main list of text messages.
