Hello bayla,
Kindly download the following file and see if it helps:
http://d2.brillkids.com/upload/files/MaxLocksPerFile.zipYou will need to extract a file called 'MaxLocksPerFile.reg' inside this .zip file using an extracting program. In case you don't have an extracting program yet, you may download WinRAR here:
http://www.rarlab.com/To extract the file, simply find the 'MaxLocksPerFile.zip' you've just downloaded, right-click on it, and choose 'Extract Here.' Double-click on the 'MaxLocksPerFile.reg' file to run it (make sure that Little Reader is closed before doing this).
Once you're done running the .reg file, you may open your Little Reader and try importing lesson content files again.
I hope this solves the problem!