File exists. It was working fine until the last reboot. However it's not updated when you attempt to run it using the network account. If I switch it to Local System it starts, but I can't run it that way. Here's a typical log for that situation:
2012-08-19 03:01:07 - ? [100] Microsoft SQLServerAgent version 9.00.5000.00 ((Unknown) unicode retail build) : Process ID 6016
2012-08-19 03:01:07 - ? [101] SQL Server servername version 9.00.5057 (0 connection limit)
2012-08-19 03:01:07 - ? [102] SQL Server ODBC driver version 9.00.5000
2012-08-19 03:01:07 - ? [103] NetLib being used by driver is DBNETLIB.DLL; Local host server is
2012-08-19 03:01:07 - ? [310] 4 processor(s) and 16381 MB RAM detected
2012-08-19 03:01:07 - ? [339] Local computer is servername running Windows NT 5.2 (3790) Service Pack 2
2012-08-19 03:01:08 - ? [432] There are 11 subsystems in the subsystems cache
2012-08-19 03:01:13 - ! [364] The Messenger service has not been started - NetSend notifications will not be sent
2012-08-19 03:01:13 - ? [129] SQLSERVERAGENT starting under Windows NT service control
2012-08-19 03:01:13 - + [396] An idle CPU condition has not been defined - OnIdle job schedules will have no effect
2012-08-19 03:01:17 - ? [131] SQLSERVERAGENT service stopping due to a stop request from a user, process, or the OS...
2012-08-19 03:01:30 - ? [098] SQLServerAgent terminated (normally)
all starts and stops, user assignment, is being performed in SCM.