Just to confirm, I'm seeing this issue with my TSU9400 (haven't checked my TSU9600 yet). When the backlight times out, it drops the wifi connection and can take ages to get it back (minutes sometimes). I've changed my RFX9600 to use DHCP and the TSU9400 is using a fixed IP (and similar Pronto network settings to what's been recommended in this thread)...and I'm using WPA. I'll look into changing over to WEP128 but that's not ideal from a security point-of-view, especially seeing my "Pronto" access point (Netgear WG102) talks to my main wireless (N) network.

Be interesting to see if this is addressed in a firmware update. I'd be happy to offer up a complete list of my Pronto/RFX settings, router make/model/firmware etc if that would help the Pronto team?