I get the same issue occasionally on an Nvidia card.
http://pastebin.com/zQCUmx0r
The pertinent bit seems to be:
DebugMessage: DX Error: Invalid call
Debug Message: ERROR: Failed to set ambient color to -1 in ::SetAmbientColor
DebugMessage: Error flipping back buffer to primary buffer.
DebugMessage: Invalid call
DebugMessage: Main Shell terminating normally
Figured I'd share, in case more data helps.