Like the title said every time I run Imobster I starts up but if I try to play it keeps the last screen up
Settings, apps, manage apps, all, find your app and wipe cache. See if that fixes the problem. If not try reinstalling the app.
-take control of your nexus experience: Make the Vzw Galaxy nexus your Galaxy Nexus. Fastboot oem unlock (to find out how ask a rescue squad member).