This is a generic error from adobe which means the file is not supported for the version installed on the machine. The best approach is to convert the file to a different format.
However, you should note, due to the hundreds of different encoders available today, it is possible that some of your files may not run properly in your signage presentation.
That is why we highly recommend you use a Freeware utility like Super to convert your media files to standard format including FLV, PNG or SWF. This will eliminate any encoder /decoder issues you may experience.
Download the Free media format converters here:
http://www.freemake.com/
http://www.erightsoft.com/SUPER.html
Where can I find a previous version of the SignagePlayer software?