As a workaround, try using the 'v7.3' flag from the command window while using "save". Large files require using this flag when working with "save".
For example, to save the variable 'D',
save('DVal.mat', 'D', '-v7.3')
You can set 'v7.3' as the default in -
Preferences --> MATLAB --> General --> MAT-Files
Secondly, loading a MAT file which is still being saved in the background or which was interrupted halfway through (because of closing MATLAB, or any other reason) results in the error "File might be corrupted".
Hope this helps!