Thats the exact reason why!
javaw.exe is used by Azureus,a very popular Bittorrent P2P program.
Internet Mail provider doesn't bother if it's really a POP3 connection or not,if it hits port 110 it will try to check it. Now here is the problem.
Some users set ports to be random from 0-65k. So when Azureus gets request through port 110 by javaw.exe, avast! Internet mail will try to check it, but since it's not a real POP3 connection, avast! will display Timeout messages. Thats why it should be excluded from Internet Mail.