Is this a windows job? is this on a heavily used machine?
I have seen such issue occur it if its a heavily used machine it could be an issue with the number of open files/processes.
if this is a dbproc jobtype it could be a setting you need to update in agentparm.txt It has to do with the threads etc, need to set to 0.
if we can get more specifics those of us that have lived through such issues may help.
Hope this helps and good luck
Steve C.