Now that I think about it, this did infact happen to me once. But for the life of me I can't remember how to fix it. It wasn't in a configuration screen or anything like that. I'm 99.9% sure my solution took a call to tech support. And even they took a little time with it.
I'm sorry I'm not much help.
Although, an interesting observation that both I and a collegue of mine noticed at about the same time was that if you install both Proworx NxT and RSLogix on the same PC, their bugs tend to cancel each other out somehow and they both run better.
Sounds weird, but it's true.