Why am I not getting events on one machine?

[ccscowboy]

I have a C# app which retrieves data using get_RequestHistory. On my laptop, the app works fine; on my desktop machine, ON_BARS_RECEIVED never triggers - I don't get any data. Both machines are running XP SP2, patched the same. The eSignal app works fine on both, which makes me think it's the interop layer, assuming the eSignal app uses the ActiveX control directly.

Any ideas? Would be really nice to be able to move development back to the desktop machine.