Sudden HTTP ERROR: 503

[Zoll13666]

I've had subsonic installed and running on the same computer for about 6 months now. Suddenly about a week ago it stopped working and gives me a HTTP ERROR: 503 service unavailable when I try to get there from the computer. I don't know whats causing this, no new firewalls or anything have been installed. I've re-installed it several times to no avail, if any one could help the it would be appreciated.