Sametime: Resolving "There was an error opening a chat session…" errors

I recently encountered the following error message when trying to initiate a chat session with a colleague.
 

 
Apparently, the error “0x80000005” means “The element is non-existent”. What happens is that when I tried to initialize a chat with my colleague, the Sametime client tries to open a Sametime channel to this user. It seems this is so rare an occurrence, the client hasn’t been programmed with a proper error message.
 
Luckily, the problem is resolved fairly easily. Logging off and on Sametime has resolved the problem for me.