Check your drive letters setting under 'My Computer / Manage' , if the letter that were assigned to the card previously are now used by another device, then it could cause the SD card not to get a letter, hence not showing up under My Computer.
dimsums
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May be your adapter, I am just guessing here, but if the reader is of an older type and the cards are newer such as SDHC type, then it could cause read problem, but seriously, looking at your post, the problem dont seem to have an logical answer. What I would suggest is to use teh card reader and the 2 problem cards on a different computer, if you hit the same issues, then it could narrow down to the card reader or even faulty cards, otherwise, its a software/Windows problem on your PC.
dimsums
Junior Poster in Training
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Ok, this narrowed down the possibilities, if the memory card works in a camera or your cellphone, then chances are your card reader is not totally compatiable.
dimsums
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71 posts since Nov 2011
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