[caldair]

I cannot say difinitively what type/brand of card will work. I have not seen any trend in the types of cards that do not work for people... maybe someone else has a better sense of that.
But I CAN tell you that I have successfully used this build on:

8g Sandisk class 2
16g PQI class 2
2g Verbatim MicroSD
32g RetailPlus class 10 (currently) > some people have reported problems with class 10, so you might want to avoid them.

It seems like MOST cards work, and that a card not working seems to be the exception to the rule.

Hope this helps.

Oh, and did you ever do the Full Format using the HP USB Disk Storage Format Tool like arrrghhh suggested??

If not I would definitely try that first before buying a new card.