Does the card read ok from other PC's still?
If the card is ok still on other PC's try unistalling the driver for card reader and reinstalling it, the driver maybe corrupt or Windows may find a more compatible driver. Right click start choose Device Manager, expand Disk Drives (it might be under another
heading so you might need to look under other headings for it) double click the Card Reader, go to the Driver tab and click uninstall. When that is removed reboot and try again.
