Problem with apps not launching from the SD Card

[rg3000]

A couple of apps that I have, angry birds is one of them, it installs fine then the next day the shortcut will disappear from the phone. (inspire 4g)

I can look at the SD card and it is there but I cannot move it to the phone and I cannot start it from the SD card.

I have a couple of apps that do this.

Thanks