I had the same problem on two different computers. Fixed it by going into the advanced settings and deleting all the data files on the computer and then deleting the data files on the usb stick. Here are instructions.
Step 1: Delete data stored on computer.
Restart computer (required)
Open Data Manager
Click 'Options...'
Click 'Advanced...'
Click 'Open the download folder on this PC'
Delete all files -and- folders except files that begin with the name 'DataManager'
Step 2: Delete data stored on the memory card.
Delete the 'ChartData' folder on the USB flash drive
Step 3: Download Fresh New Data
Click 'Update Now' to download a new data to the computer. Once downloading has finish, data will be copied to the usb flash drive. This can take awhile because of the volume of data.