how to rtroubleshoot hung sql server job?

This is sql server 2005(SQL server 9.0.5000). One sql server job is used to kick windows batch file.It runs hourly every day.

These days, this sql server job always hungs sometime.But I don't why it hungs and how to troubleshoot.

I let output job step generate output.Log file is:

Job 'job1': Step 1, 'XXX' : Began Executing 2013-12-28 07:30:00

I don't why it is hung and how to fix this issue.

Any help?Thanks