I had almost the same problem, except i haven't changed the password or something else on my wireless network. My X8 couldn't see the wireless network with both versions 1.6 and 2.1. So after I've updated to 2.1 i changed the wireless network channel from 12, how it was in the first time, to any channel from 1 to 9 and it works great on all those channels. Also I've changed the name of the network in something simpler, the old name had a lot of alphanumerical characters and the channel I've let it between 10 and 13 and ... it didn't work; so i putted back the old name (xXX-XXx_xx xX, something like this) and changed the channel form 1-9 and ... it works
So i think in this case the problem seems to be the length of the channel, it has to have only 1 digit. Hope it helps.