Thanks for your reply...(apologies for my slow response....UK time difference.)
I have just copied 'Wall Street' to both the device and card. The device playback is fine, but the message I get with card playback using the card reader/PC is 'Error can't open file. The Media type of file is not recognized'....On the device it says 'Video Problem...Can't play this video.' ? Thanks again if you can come up with any ideas. (nb I have tried copying both 'off line' with the card reader, and a direct USB connection.)
You are welcome Mike,
How large are your video files?
With memorycards, anything over 4GB in size will have issues similar as to what you are experiencing. With DVD-sized content, you shouldn't run into this (unless you used a 1080 profile for the conversion), but if you are converting your movies from 720p or 1080p sources, it isn't hard to run into this file-size limit.
If the files are less than 4GB in size, it is the card that is the problem. Since the video file is fine (plays from memory on your device), but doesn't play from the card on both your device and your PC.
3 cards with the same problem is a bit strange, but if you purchased them from the same seller, it is quite possible.
On a (very) regular basis I get questions from people with similar complications, and one of the first things I ask if they are using memorycards purchased "for cheap"
In particular eBay, but even some respectable sellers, are filled with offers ("too good to be true" deals) for "fake" memorycards. low-capacity (1-2GB) cards, rebranded and reformatted to appear as high-capacity (16-32GB) ones. Most people will take quite (longer than the return period) a while before they run into problems. Use it for a few pics and a few mp3's, but with these cards, if you copy over more stuff than what the real storage capacity is, it will become corrupted. Putting one video on it works fine, but as soon as you go over the 2GB, everything new appears to be on there but doesn't work.
Some sellers don't know that there are issues with their cards, others do know, and just rely on the fact that the majority of people take a couple of months to fill up the real capacity.
But there are also bad cards. A few months ago, I picked up a 64GB (class 10) card from Sandisk directly (through Amazon), and that card was just bad. I had 20+ TV show videos (all working) lined up to copy onto it, and after copying half of them were corrupted. File-transfer was also quite slow compared to other cards I have.
When I formatted the card, and copied the same shows back onto it, others ended up corrupted and ones that didn't work before worked again.
I hope this helps Mike.