Twice now I've had exceptions begin to occur on pages that were working just fine.  I always get "External module has thrown an exception" and an internal stack trace.  In effort to determine the exceptin thrown and attempt to fix the issue, I launch VWD and run the site in debug mode.

Both times now, the exception magically does not occur when running the site via VWD.  In each case, the exception also goes away when using the site normally.

Any idea what is causing this?

I've never done any ASP.NET development, although I'm interested in learning.  Any pointers would be helpful.  www.adefwebserver.com is great.  I've been to www.asp.net, but it's a little over my head just yet.  I'm also looking at the dozens of books available and trying to decide which one to invest in.

Thanks