OK, almost a year later, I found the problem! It was too late to roll out this version, so they're just doing it now, and the problem has reappeared. The unit value is passed
into a front panel control from the calling vi. On the versions that
don't work, that control is HIDDEN, and the RingText.Text property read doesn't always work. On the version I posted
here it's visible. The versions with the hidden control may not always
screw up, but making the control visible seems to cure the behavior.
