With the MMC in the logger, press [2][2] from the main menu. This will bring you to the MMC status screen where you can see the number of files that are on the card. If there are files showing here, Windows should be able to get at them.
If you have a USB MMC reader, try installing it in different USB ports. Alternately, try installing the MMC reader in a different computer.
If there are files on the card, but you still cannot get it to read properly, contact support@nrgsystems.com for a return authorization for MMC data recovery. NRG has special utilities for extracting data.