Similar issue here but doesn't look like there was a resolution:

http://support.empirisoft.com/showthread.php?t=2404

These errors all occur (in most cases) because MediaLab can not write new data to the data folder. There are a few reasons this can happen.

  1. Data files are already open (although ML would normally tell you this at the start of the session)
  2. Data files are read only--this can happen, e.g., if the experiment and its data folders were copied off a CD which causes all the file to become "read-only"--right clicking the data folder to check for "read/write" is a good check here.
  3. Data files are located in a folder that has user rights protection (see link above)
First thing I would suggest is to ensure that *all* files and folders are closed when you start your session. Does that make a difference? If not, then the next thing I would try is to backup and then delete the data folder and run a test session--does that resolve it? It may be that there is a corrupt file and starting fresh will resolve it.

If none of this works then let me know and we can do some more in depth trouble shooting.