Hello - we are seeing this same behavior on a variety of browsers, but often only against a single pair of our controllers (FAS3250, 8.1.3 7DOT). We've temporarily "fixed" it by clearing browser cache/cookies and closing the browser before giving it another shot. We've got another pair of the same 3250s running the same DOT and we've never (knock on wood) experienced the behavior against those.
That said, it's fairly intermittent and always very annoying when it happens. I just ran into the problem this morning and switched over to the dreaded IE, but still getting the same behavior. Currently running OCSM 3.1 but my colleague is running a newer RC version and he'll see the same thing about the same frequency as I do.
We used to call it "System Mangler" but until this behavior, the newer versions have treated us pretty well. Hoping this can get fixed soon...
