Intriguing! Perhaps: the Windows server which is running your instance of a (remote) outlook client is misrouting the interprocess signals from its (remotely-hooked) mouse driver process?
Or perhaps some process on that server (and on my laptop) is generating spurious mouse scroll-down signals?
And/or perhaps there's a dll versioning problem in both "your" Windows server and my laptop which is the root cause of the confused signalling?
So many possibilities... and we're not gonna localise this defect in a chat stream! However AFAIK it's still nonreproducible -- occurring sporadically, often enough to be a major annoyance to users but quite-probably not often enough to be localised -- so I'm not gonna hold my breath for Microsoft to repair the defect. Instead I'll be trying to collect enough info about *my* platform's exhibition of this defect that I can create a defect report that'd be helpful to MS's QA team.
A (2002!) slideshow from Rational offers the following advice to QA teams when writing defect reports:
"Analyzing Non-Reproducible Errors
"Always report non-reproducible errors.
"If you report them well, developers can often figure out the underlying problem.
"Describe the failure as precisely as possible.
"If you can identify a display or a message well enough, the developer can often identify a specific point in the code that the failure had to pass through."