>Thanks Neil. I've had some great suggestions and will implement them all one by one until this is gone. I'll post the results when I finally have achieved success...or will post again if nothing helps ;-).

Once upon a time I got rid of 1104 by turning off the QoS service (it's in the network connection properties) on the workstation. It tried to be smart and closed the idle file handle on me, which I wouldn't discover until I actually tried read more records from the file, or write to it. An app waiting for user input would work fine until they gather at the water cooler; when they come back, bang. Timed out.

It's the last resource, of course, and I guess it's smarter now - the above story was in 2002. I'm throwing it in in case nothing else helps. Though, QoS is turned off on my machine :).