Originally posted by Tom S. Is the card reader a SD or a SDHC reader? If it's a SD and your card is a SDHC, it will not work. BTW: is the computer saying you need to format the card, or asking if you want to?
B&H is offering an inexpensive (USD $9.95) GGI reader that's identified as SD/SDHC. Not sure if this is the one. Can you confirm the reader model and/or its age? It's been a long time since a serious reader manufacturer made an SD-only reader.
Another reason I stay away from the $1.99 specials - I don't need a reader corrupting images. All my active readers are Sandisk MicroMate. Pricey (!) but they don't keep me awake at night.