My Olympus digital camer uses a Multi Media Card to store data and I bought a USB memory card reader to transfer the data to my PC. Lo and behold, after transferring some photos to my PC I put the MMC back into the camera and it didn’t work. I was quite puzzled as I was pretty sure the card should have worked – it worked fine in my PC. Anway, I rubbed the chip on my jeans to clean it off…and it worked just fine. There’s a tip for you.