I've just started noticing a strange problem. If a host being monitored by a distributed server dies the master server isn't receiving the information it needs to generate an email. This doesn't happen every time only on occasion but I can't figure out why it's an intermittent problem.

This is an excerpt from the logs on the master:
[11-09-2009 14:05:56] SERVICE ALERT: prodhv28;Alert 11003 - Check Local Disks;CRITICAL;HARD;1;CRITICAL - Plugin timed out while executing system call
[11-09-2009 14:05:26] SERVICE ALERT: prodhv28;Alert 11002 - Check Load;CRITICAL;HARD;1;CRITICAL - Plugin timed out while executing system call
[11-09-2009 14:05:16] HOST ALERT: prodhv28;DOWN;SOFT;1;PING CRITICAL - Packet loss = 100%
[11-09-2009 14:04:56] SERVICE ALERT: prodhv28;Alert 11002 - Check Load;CRITICAL;SOFT;1;CRITICAL - Plugin timed out while executing system call

But this is what I see on the slave:
[11-09-2009 14:06:50] HOST ALERT: ashprdhv28;DOWN;HARD;3;PING CRITICAL - Packet loss = 100%
[11-09-2009 14:05:29] SERVICE ALERT: ashprdhv28;Alert 11003 - Check Local Disks;CRITICAL;HARD;1;CRITICAL - Plugin timed out while executing system call
[11-09-2009 14:05:29] HOST ALERT: ashprdhv28;DOWN;SOFT;2;PING CRITICAL - Packet loss = 100%
[11-09-2009 14:05:06] SERVICE ALERT: ashprdhv28;Alert 11002 - Check Load;CRITICAL;HARD;1;CRITICAL - Plugin timed out while executing system call
[11-09-2009 14:04:24] HOST ALERT: ashprdhv28;DOWN;SOFT;1;PING CRITICAL - Packet loss = 100%
[11-09-2009 14:04:04] SERVICE ALERT: ashprdhv28;Alert 11002 - Check Load;CRITICAL;SOFT;1;CRITICAL - Plugin timed out while executing system call


The two subsequent host check attempts never made it back to the master. I'd chalk it up to a problem with nsca but I'm not missing any service checks, only host.

I've currently got every host using the same template, which includes a 5 minute check interval with a 1 minute retry and a 600 second freshness threshold. Somewhere one of the servers should be kicking off these checks but for some reason the master isn't doing what it's configured to do. I'm at a loss. Any ideas?