This is your main error.

HTML Code:
2007-11-27 17:48:44 Thread-189993 ERROR util.files: ERROR: nmeufos_new: failed in lfiopn on file: /oracle/product/agent10g/sysman/emd/agntstmp.txt.error = 24 (Too many open files)
2007-11-27 17:48:44 Thread-189993 ERROR pingManager: Error in updating the agenttime stamp file
i think this is not agnet issue but OS issue.
Agent is not able to run(edit file agntstmp.txt) because of OS settings.

Check this BUG :- 6439387.
bug is for solaris though...