Hi guys,

I had the same problem with skype and msn, e.g. the skype and msn would work for more than a month and all of a sudden will stop with an error message "network error". BTW I am using msn (haze).
After trying all that was advised above and being certain that skype and msn would not work under neither wlan or umts, I tried the following which worked it out for me: Turn off the phone, remove the battery and sim for a minute, then reasemble all and boot. It worked straight away.
NOTE: Be advised that prior to that I tried just rebooting, loging with different account, etc.... Any of these might have had affected the final test somehow!

cheers!