PLEASE HELP!

I have recently bought the HTC EVO. I upgraded my memory card from the stock 8gb card. I had downloaded movies to the 8gb card and they worked flawlessly. However; when I tried putting the same amount of files on the 32gb sandisk sdhc card and the first couple of movies after formatting them worked well. After the third movie, and with plenty of space left on the card, the movies would transcode to the card, but they would show up as grey and said "sorry, this video cannot be played"... Yes, I bought the card off of ebay and have heard of the fake cards being sold. But all 31.05 available space shows up on my phone. Why can't I get these other movies to play? is the card defective? I did format it to my phone and I even did a hard factory reset. It still does not fix this problem. Any suggestions?