Lightroom: "Video System Error: Unknown message: nextFrame"

When working with Canon 7d video in LR 4.2 (and past versions) I frequently get the error "Video System Error: Unknown message: nextFrame".

This usually happens when I've ben viewing the video in Loupe view (E) and drop back to grid view (G). I might have some thing to do with the fact that I'm attempting to reject the video while in Loupe view. I've been scrubbing through the video with the mouse, stop scrubbing, hit X but nothing happens so I try to return to the grid with the G key so I can reject it. I reject it and attempt to return to Loupe view but get the error. After getting this error I cannot view anymore videos until I close and reopen LR. If I don't exit LR and try to view another video I just see one of the frames from the video that threw the error and the error reappears at the top.

In the past I'd seen this when working with files stored on a network location. This is not the case this time. The files are on my local disk and have never been anywhere else. They came straight in from the camera today and have lived there since.