Well, I may have fixed my Pronto. How? Trying all sorts of settings on my wireless AP and eventually, switching it to 802.11b only (rather than g&b). It would now appear to connect to the wireless network everytime.

TBH, this is not a problem because with the iPronto on the wireless network it (the wireless network) would only ever work at 11Mbps anyway and I have now removed all my other 54Mbps wireless bridges and replaced with wired connections.

I reckon there is something in the later firmware versions (1.6.21 on) that has caused this. Will be good to see if Philips identify and fix it (maybe that's hoping too much), but for now I'm happy again and hope it stays this way.