Hi OzViewer, please provide more details about your computer and the Slingplayer version that you are using, have you tried to use your Slingbox in Watch.slingbox.com.
Besides check the article below in case you are using HDMI in your set up box.
The problem exists on more than one computer so the conuter isn't the issue. I am using the latest slingmedia version, 2.0
The slingbox has come good by itself. Nothing changed but it started working again.
Yes, the panasonic blue ray recorder is connected to my tv via hdmi but that has always been the case, installed some 9 months ago.
I had previously tried remotely turning off and on the device with no success.
Then one day after turning it on it started working again.
When it wasn't working it also didn't work on slingbox watch.
The problem is back again.
I switched the inputs around between the Panasonic Blue Ray Recorder and the Foxtel (IQ2 now) box and no the Unsupported Video signal is on the Foxtel box periodically. It seems to be ok for a while, maybe 30 minutes to 60 minutes, then I get the error. Changing channels clears it for a while, or remotely switching inputs but then it comes back.
I don't have the slingbox connected to a TV and i only use it remotely.
Searching the web it seems to be a common problem dating back to 2010.
I am surprised the Slingbox techs still haven't fixed the problem.