Yes, either they are burning them wrong, or the 5K does not like the media they are using. More likely the former than the latter.
I have been able to successfully update several times on many players to 1.6 using either Toast 10 for Mac or Apple Disc Utility on Verbatim and Memorex CD-Rs. My original disc was a Verbatim and worked flawless many times, then I sent it to a member here and it worked for them. The one I am using now is on Memorex and I wrote to that for grins since I ran out of Verbatim, but kept 2-3 on reserve just in case. With 1.5 I have a Kodak CD-R/W and did not bother to format and rewrite for 1.6 since I was in a hurry and wanted to preserve the disc in case I had to go back.
Those of you getting bad discs from Samsung should note the manufacturer of the media and also check the integrity of the disc using a computer. I would compare it to an older disc you either burned or got from them before and make sure they did not just burn the image file to a CD-rom format file rather than burn an image to the CD. I bet you will find that the name of the downloaded file is just in a folder or in the root of the disc. If that is that case, that is the problem. Another thing to check is that they are using a CD and not a DVD. I made that mistake once and got some very strange results, took a long time to write the DVD, which does not make sense and of course the disc could not be read.