Try a reboot of the host.. that will ensure services didn't hang during a restart.
If that does not work, please review the sever.log and provide the output.
Could not reboot at the time due to active jobs. Noticed an OpsCenter process hanging around even after running opsadmin.sh stop.
Killed that process and restarted each piece in turn (pbx, at, db, and server) and it works. Odd.