[Dovecot] Timeouts

Hi All - I have a dovecot imap server that I've been running merrily for 6 mths now - the 2 clients that are used on it are evolution and outlook 2003 - I daily have timeout "closed connection" issues with either of these. I have the outlook idle workaround enabled, but I dont think thats the issue - can anyone give me a hint how I can start to trouble shoot this? Thanks Glenn