Hi. I will attach a zip. Inside you will find the original mesh at "/Mesh/BlockGuy.blend", the rig (which proxies the mesh) at "/Mesh/BlockGuy_RIG.blend" and then the corrupted file is at "/Anim/BlockGuy_Anim_Walk.blend" (which proxies the rig).

Also, if I select some keyframes, I can't deselect them by just click in empty space. I opened up a new file and this is working there - just not in the previously described corrupted file.