I open spark every morning at roughly 8am and use it for the first hour.  I have a few chats back and forth between other users, then end up closing the chat windows so I no longer have any chats up in front of me.

Then, within the next 5-20 mins or so, I go back to the list of users and try to double-click to open a chat window.  No windows open.  I even highlight the user and press Enter, and it does nothing.  I do find that the users window loses its focus when I try double-clicking a user, as if there was a chat window actually opening, but there are no other windows opening.  I have to log off/exit spark and log back in.

I've also checked for updates and there are none.  I am on Vista, which I think might be the issue.  Any help is appreciated.