Frequently Ill put a SD or CF card in the internal media card reader and it disappears from my computer and device manager. No error just gone! The only way to get it back is power down system and "Unplug" power cord. Works for 2 or 3 times and the same thing happens. Dell tried a few software and settings fixes but that didn't work. Then the sent me a new media card reader but same thing happens. Now they want to replace the mother board and power supply but I doubt that's is too.. Any SOLID fix yet?