Not all card readers can read SDHC cards, and it looks like you have one of those readers. Good news is, you can find cheap card readers for like $5 that will read SDHC cards.
I have a 4gb Scandisc Micro SD HC card. I works on other computers but not mine. System Info: Windows 7 Home Premium 32-bit; AMD Sempron SI-42; 2gb DDR2 Ram, 250gb HDD. My Micro SD HC reader is recognized but when click on Browse Files the files are not available. Help will be much appreciated:)