Look at the job status with
qstat. The next to last line of the output is a comment describing the job status. Possible outputs include:
qstat -f yourjobid
Job is running OK
Job requires more memory, cores, or nodes than currently available, or you have requested more resources than what is available.
Delete and resubmit job.
Job will not run because the resources are reserved for other jobs.
Try deleting the job with
qdel -Wforce yourjobid