N900 Crash if Guest Access Enabled

Bought the N900 Monday to replace a D-Link that died after many years of service.  Worked without any trouble at all until Wednesday morning.  After enabling guest access, things were fine for a while, but then I lost all connectivity (could not even browse to until I power cycled.

Hoped it was a fluke, then some time later it happened again.

I have again disabled guest access and…so far, so good.

Has been at firmware 1.05.12 since updating upon initial installation.

Have you tried factory reset setting after upgrading, I was also facing issues with the wireless but after factory reset in the Admin settings everything is good.

I assume that if I do a factory reset I will lose any customizations (I’m especially concerned about DHCP reservations).  I realize that I can back up the settings to a config file (in fact, I’ve already done so), but if I restore from that file have I essentially un-done the factory reset and lost any potential benefit?  Am I being too paranoid?