Bad news

It looks like the server's playing up again.
I'm getting exactly the same problems again - the server seems to be timing out when changing folders and opening emails that aren't in the Inbox.
Is there anything else that can be done in order to try and fix this?
I'm positive that this isn't a confguration problem with my Thunderbird client, because I never used to have problems until the last few months.
Any ideas?
Many thanks
Oliver