Yet another ailment of the internet variety.
The screaming frustration caused by seeing a friend leave a message on a board, in Everything, or receiving an email and knowing that you've missed them by milliseconds. And not being able to do a damn thing about it.

Symptoms include smacking one's head into the keyboard, flooding said friend with "are you still there, come BACK" messages in the appropriate forum and the development of ulcers at a young age.

Cures probably involve getting a life.