Renishaw 1093 Probe Fail Alarm

When trying to probe my workpiece with a Renishaw OMP40-2 probe, the probe touches off on the surface of the part, returns to its previous position, then the machine displays a "1093" Probe Fail" alarm. The machine is a Haas VF-2 mill. What could be causing this? I was probing a relatively small part (4"x1"x4") in a vise, so I doubt that something could have been blocking the signal to the probe. Earlier in the day when probing a similar-sized part, all was going normally. I know what alarms come up when the batteries die or when I'm too far away from the surface I'm trying to probe, but this is the first time I've seen this one. Tomorrow I will check everything, probably recalibrate the probe and change the batteries for good measure; call Renishaw if all else fails. But in the meantime I wanted to know if anyone else has had this issue before and what caused it. Thanks.