I am trying to do the operation from apex data loader and am getting the below error:

You are seeing that this error had occurred after processing of 14,400 records. But if I re-run the process again from starting, I am getting the same error message again at say after processing of 15,600 records. Similarly in the next try I am getting this error at say after processing of 4,000 records.

This is only happening when I do this at my office. But strange thing is that if I do the same operation at home, I am able to accomplish my task successfully with out any error.

So, please help me to trouble shoot this issue. Is this issue related to firewall/web-sense?