silvercircle,
It may be that the server was indeed busy, especially when a recent update had been issued.
Have you tried to update the db since the problem arose?
Normally, Avast 4 will retry to establish server connection with one of 3 servers used to update the db (provided you have Avast set for auto updating.
If the connection was terminated, this can occur when you ISP server dumps the line. There are many reasons for this, but none that are directly related to your system unless the condition persists.
If you are still having problems, try to give me some additional information:
Have you set Avast 4 to auto update both program and db?
Will a manually update work?
What OS are you using?
Thanks