If you find that Moom's mouseover pop-up panel works for a while, then stops, there are two things to check:

1. If you have Moom set to run at login (in your user's Accounts > Login Items list), make sure the "Hide" box is not checked. If hidden at login, Moom will not function properly.
2. If you use a Logitech wireless MX or Revolution mouse, try unplugging and then replugging the Logitech USB receiver. For reasons unknown to us, it seems that Logitech's driver starts intercepting Moom's 'show hover panel' requests. Resetting the USB receiver fixes the problem.

If you try both these fixes (assuming they both apply) and still have issues, please open a trouble ticket, and we'll figure out what's going on.