Odd USB Pen Drive behaviour

[#1]

Bought a 64GB USB Pen Drive as recommended in another thread.
First time I used it was to transfer about 15GB of HD camera footage from the laptop to PC. No errors reported yet when I tried to play the copied files from the PC very few would play in any of my players. Those that did play did so without fault.
I then tried to play direct from the pen drive connected to the PC with the same result yet putting the pen drive back into the laptop all the files played without issue.
Any clues on this?
Edit: Definitely not a codec issue as I copied the same files to the PC direct from the camera and they played ok.

[#2]

To decide if the usb drive itself is at fault you need to compare the file before and after putting it on the drive.
In other words you need to find a program that will calculate the MD5 hash of the file. Get the MD5 hash of the original. Put the file on the drive, unplug, plug back in and copy it off again. Get the MD5 hash of that file that has come back from the drive. If it matches the original then the file itself is OK. If it does not match then you have a faulty drive.
MD5 programs are available on most download sites but if you can't find one I have one that I put together using TPLockbox components a few years back.

[#3]

Oh dear, have a read of some of the neg feedback.
http://feedback.ebay.co.uk/ws/eBayISAPI.dll?ViewFeedback2&userid=rubyisland&iid=281138759205&de=off&...

[#4]

Most of these are fakes I'm afraid. They are usually 4 or 8Gb drives which have had their firmware altered to look like higher capacity drives. You'll write the data and when it runs out of space, it will loop back to the beginning and overwrite the original data.
The fakers have even go so far as to fake the SSD drives in a similar manner

The best thing to do is to run h2testw (free) which verifies all of the drive.

[#5]

Times are getting harder in china too if they're turning to cons to make a profit 

[#6]

I won't buy off Ebay. I had one annoying experience which put me off.

[#7]

I buy about three or four items a week using eBay, and while there might be say a problem with 1% of purchases, those problems have nearly always been resolved satisfactorily.  I have had many more problems buying NEW items from Amazon sellers, particularly with goods arriving that bare no resemblance to the pictured item, or are foreign imports sold as if UK models.
My only real gripe with eBay, is that I disagree with their policy about the BUYER paying return postage when items arrive broken or are the wrong item.
I would use eBay more than I do now, but their 200 "Watched Item" limit is way too low and needs too much effort to maintain.
The 100 "Saved Searches" is ridiculous too, I have five accounts just so I can have 500 searches,  but I could easily use more.

Coincidently, I also bought one of the "Gold Bar" flash drives, but 32GB and from a different seller with much better feedback.
It arrived yesterday, but I haven't had the time to open it or test it - but I will let you know how it goes using Linux drive verification tools.

[#8]

I've bought quite a lot from ebay but like all MARKETS you have to be a bit careful and be prepared never to get a resolution from the seller if things go wrong. That can happen at any market / boot sale you go to aswell you know. Just because it's 'ebay' doesn't mean every seller is like that.
There is far too much anti-ebay out there yet people will happily go to a boot sale and buy something thats 'working' on the say so of the seller and in reality whatever that item is could also be duff too but in the meantime your seller has taken your money and vanished.
I've bought quite a lot on ebay and yes I've had the odd few niggles but I wouldn't avoid it just because of them. You just have to do your research on some items, look at feedback, decide if its an acceptable loss if things go wrong etc.
Bought a USB hub (well no technically it was my partner but she bought it for me) that was meant to be usb2. Seller sent a usb 1 hub instead. Checked his other listings and he was basically trying to get rid of old usb1 stock that no-one wanted and was chancing it that most folks wouldn't notice. Sent it back, got a refund and then the islamic abuse came through by ebay messages along with a non-payment etc. Ebay saw sense and dealt with the non-payment thing but it taught my missus a lesson! Had another electronic item a few months back.. sold as new, turned out to be second hand and then sizzled. Arranged to send it back and got given a business address yet he claimed to have bought them last year himself from ebay and thats why he had no warranty to offer  - in other words it was ex business stock that had been used and re-boxed and they were trying to avoid the business charges on ebay  
@purleigh my missus has bought several things via amazon that haven't turned up. It seems amazon is the wild west for independant sellers compared to ebay.

[#9]

Just started a PayPal dispute over my 'faulty' 64gig Gold Bar usb memory stick!
Seller now has 20 days to respond!
I'm not holding my breath!
Thanks to Mav for the heads up! 

[#10]

I've deleted all files from the 64GB pen and running h2testw as suggested by picbits.
It's reported there are 64GB but it is indicating that it will take around 12 hours to test it. That seems an extremely long time

[#11]

Indeed - as these drives get bigger, they take longer to test.
You may find it's a much smaller drive and will start to show errors well before the 12 hours.
I was looking at 64Gb drives earlier for my television (it turns out it won't use a USB drive anyway) and the cheapest retail I've found is around £20 delivered for a Maxell 64Gb USB stick.

[#12]

The Linux tools that I plan to test mine with, usually take about 12 to 15 hours (for the short test !) on 250GB/320GB hard drives, so I'm not particularly surprised by that figure as a USB stick has a much lower write speed compared with SATA2 drives.

[#13]

It's running on the laptop which I'm not needing at the mo.
Tomorrow I will be dissembling my PC to give it an autumn clean and insert the new SSD

[#14]

Just as long as you didn't buy the SSD from the same supplier 

[#15]

Mav did you try what I suggested?
MD5 hash comparison will tell you almost instantly if the file is different once it's been on the drive. Granted you might need to try it a few times but it will work.