Probably you see a red sign in the lower right after the error occurred. Can you click on it and look for more details regarding this error and post them. It would be good to where the problem occurs.
Alternatively you can go to Help / Open Log Directory and attach the most recent file here. It should contain more information.
Because of an issue in the subsetting function you should save the product to BEAM-DIMAP after resampling or remove all the masks. I have explained it recently here: