This is due to various reasons such as space constraint, no.of cab files generated, size of cab files...
A simple way to fix this one is: go to the export file location. Open the last and 2 cab files and you will see some xml files. Copy all the xml files.
Keep it in a temp location.
Open the windows temp folder by typing %temp% in start -> run
Run the import command.
if a new folder with guid created under windows temp folder
pause the import by pressing break button
copy all those xml files into that location
continue the import.
Import runs fine...