I am having the exact same problem with the Optimus. I have never rooted. Basically, apps keep disappearing from my device and I have to reinstall them. It is different apps every time. I am not sure whether they are actually uninstalling or just disappearing because usually when I reinstall, my settings are still there. So somehow it is saving my settings even though the app disappears. It is the most annoying thing since I go to use an app and it is gone and I have to reinstall it when I want to use it. This has happened about 10 times over the last week or so. Hopefully someone will come up with a solution.
