Not sure if this problem is related, but I'm to the point of thinking that the culprit here is the monoprice switch, at least in part. I have the same switch that the OP has. I have two DirecTV HDDVR receivers and a PS3 (inputs) connected to an LG plasma (out).
After switching to the PS3 and then turning it on I get black picture at least 80% of the time. I then have to reboot the PS3 to reset the video settings before I can get the picture to the TV. While I'm using the unit no issues at all.
With the HDDVRs, I can watch TV (both HD and SD programing) and switch between the two units without any issues. However, when I try to watch PPV movies, no matter the resolution (1080p or 1080i), I get a black picture and I have to reboot the receivers in order to regain the picture.
I think there's a "hand-shaking" issue that the switch is not able to handle consistently. To be fair, I do have a rather long run of high speed HDMI cable (35ft), but again, I am able to get 1080p to the TV through the switch-but only after rebooting the PS3. So I don;t think that is contributing to the problem. I thin I'll give the Sony switch a try.