Exchange 2007 OWA - Available internally but not (90% of the time) externally

[mbird]

Its baffling us, and we have tried pretty much everything - updates, etc.
It started when we had a large amount of the 'autorun' virus so Sophos was hogging all the memory.
We have since put sophos on its own server, but we still have this problem.

Has anyone experienced this before?

mb

[apearce]

I;m assuming you are using the same IIS web application to access OWA.

If you are I'm assuming there is nothing wrong with the server. If it works internally then its nothing to do with the server itself.

Are you using the same URL for both internal and external?
What error message are you getting when accessing it externally?
Is it an internet line issues - test with another internal website externally?

A.