It is possible that the Micro Track was not able to finish writing the file since the recording was longer than the amount of time available on the card. Sometimes this results in the flash card becoming corrupted. One fix is to follow the steps below.

If you are on a PC running Windows:
With the Micro Track connected via USB,
Go to Start.
Then select the RUN option.
In the box that comes up type the following:
chkdsk /F DRIVELETTER
*Substitute the letter F for whatever letter your Micro Track drive is*
This will scan the card for possible corruption and run a Fix.
after this is done, attempt to access the files like you normally do.

If this does not work, you should reformat the drive using the following method before attempting to use the Flash card again.

With the Micro Track connected via USB, Go to My Computer.
Right Click on the drive that the Micro Track shows up as then select "format."
This will format the drive correctly.