i had the new messenger installed earlier on and it worked just fine, recently i had to uninstall it and install an old version 4.7 instead.
(to link up with another program which sends messages automatically to messenger)

the same procedure was followed in all office computers.

messenger starts properly and i can send and receive messages without any problems.

however the moment i start outlook and send or receive messages, i go offline and messenger hangs. i subsequently cannot restart messenger without restarting the machine.

this only happens in my computer, although the same procedure was followed on all office computers (about 10)

any ideas what i should do?

try going to ms outlook.
tools -> options
and then the last tab (other?) and remove the ticks before the last to opions on that page..

(sorry if one of the names of menu items are incorrect i use a dutch version...)