Workflow Session hangs

I am facing a problem in Informatica powercenter 8. Whenever I run my workflow, the session sometimes hang. It shows the source rows but never shows the target ones. Keeps on running for 10-12 hours but doesnt complete it. Any idea what the problem might be?

the promblem may be with the table

i think it would have been locked

to check that just select the table and see
if it is not giving the rows then the table is locked


ask the dba's to release the locks