messenger disappears while in use

I get this problem after I got my new laptop. So I do not know if this is
related to the laptop (Lenovo Y450), or Vista (which is installed on the
laptop) or MSN... I used msn on other machines and never encountered this
problem.

What it does that while I am signed in and chatting, msn often disappears in
the middle of chat. Or when I keep logged in while chatting, it also
disappears. It also disappears in an unexpected fashion-- some times within 2
minutes i am logged in and sometimes it stays there for a long time....

What happens next is that I go to start menu to try to start it again and it
would not start. I have to go to Task Manager and ends the msn process (not
task) and then I can start it... This is very very frustrating, especially in
the middle of a chat.

I thought it might be because of the new version. So i tried different
versions and now I am using the older version. But this does not solve the
problem.

Any clue?

Thank you!