I've tried a few different versions of IMPlus on my mogul, and haven't had the best of luck.

Each one installs perfectly, and then opens fine, let's me sign in and my buddy list shows. However, when I click on a screen name to send a message, IMPlus freezes and then ultimately shuts down.

Could it be the Sprint ROM? I've not flashed a custom ROM yet, mainly because the Sprint ROM hasn't given me any troubles.