Hi Denise,

the OS is Windows Server 2003 (recommended to us by our UK OL Contact);
We do use Microsoft Exchange Server.

We usually do leave Outlook open, however what I'll do, is close Outlook and monitor the situation for the next week or so. If we receive an error in the interim I'll post up and let you know. Due to the seemingly sporadic nature of the errors, I wouldn't be able to just close Outlook and let you know if the error corrects instantly.

Out of curiosity, do OL recommend that Outlook stays closed?

Thanks for all the help!