I have a couple of these, as well as a few of its predecessor models. I've had probably 10-12 of them, and unfortunately the HDMI ports are known to just die. Has happened to three of mine. Haven't seen the checksum error myself, but a suddenly dead HDMI port is a well known issue with this whole line.
Sadly, they only come with a 90-day warranty, and in all of my failures, they happened shortly after the warranty expired. But I have others that are still going strong after 5 years or more. Philips knows of the issue, but they still won't help you after the warranty ends.
Since you can usually get them for $35-$40, it's easier to just replace them, or just use the component outputs as an alternative.
The reason I put up with this crap, is because while they are cheap players, they upscale nicely to 1080P, and they all play DIVX (.avi) files. I can also play movies right off a USB flash drive, w/o having to burn/waste a disc. (I don't have a media center PC connected to the TV). All in all, the cost/benefit works for me.