Openfire PluginManager: Unloading plugin

Experiencing a bizarre issue on one of our servers.

On startup all our plugins appear fine. After about 10-30 seconds they all disappear from the Admin console one by one and the message below appears in debug.log:

PluginManager: Unloading plugin asterisk

PluginManager: Unloading plugin cisco

PluginManager: Unloading plugin flash

No errors reported at all and the plugins work fine on every other server we’ve tried.

Anyone seen anything like this before?