Troubleshooting bridging issues

Hello All,

I'm trying to troubleshoot an intermittent issue and I'm not sure where to look to find out more information. 

So basically I have setup 2 networks. 1 guest and 1 private. The guest network is bridged to VLAN5 and the  Private Wireless network is bridged to Vlan 1

Intermittently the Private wireless network will loose all connection to everything but the router interface. For example I can't reach any computers or internet on VLAN 1 but I can still get to router setup page. 

Also a computer that is plugged directly into a port on the router that is on VLAN1 does not lose access to VLAN1 but CANNOT access any of the wireless clients.

So basically it looks like somehow the bridging of the wireless to VLAN 1 fails every so often. 

It usually resolves it self after about 1/2 an hour or a restart will help most the time..

I'm using latest version of DD-WRT Kong (Although it happend with previous versious as well)

Any advice where to start diagnosing this issue?

Thanks

MAtt