I am having what seems to an intermittent problem with sending messages to a remote MSMQ public queue, but
only when I do it from an ASP.Net web service written in VB

The class that wraps the MSMQ object with my functionality works great from a Windows forms app, but many times throws exceptions when called from the web service, "Object reference not set to a valid instance.
When we stepped through the code to find the root cause, it worked. We can't get it to fail again in the same way
But we need to track this down so we're not blind-sided during deployment

Are there any subtle issues regarding differences between Windows forms and web services

Any ideas

Thanks in advance.