i signed in yesterday night on my laptop, worked all night and hibernated in the morning as i went to work, resumed hibernation and by the end of the day hibernated once more, when i got home resumed once again, and i'm not sure when the tab title changed to "1", whether if it was right after resume or after a while, i believe it was right after resume because the other two tabs to the right are fine and i only opened them a few hours ago at home.
this can be an expected behaviour as i lost connection a few times when i hibernated or some unknown bug, anyway i leave the info and screen here.
also, if the developer reads this, it would be nice for the taskbar tab corresponding to the tabbed conversations changed title to match the name of the contact with the new message.
edit: it just happened again, now the 3rd tab changed to "1", the corresponding contact simply signed out and in again.
edit2: forgot about the rules, sorry:
windows live messenger build 0792
msgpluslive 4.01.0.240
windows xp tablet pc edition 2005