The other day I had a puzzling problem with VR objects saved out of Archicad. Some files would open in QuickTime as conventional movie files rather than VR objects. (Press play and the building spins around once for each parallel. It runs about five seconds. It's not making any sales.)
As is often the case with puzzling intermittent problems, I was working too fast and not paying attention. After running a VR and viewing it in QuickTime, I would return to AC and run it again. Trouble is, sometimes I left the VR open. It took me an embarrassing while to figure out that those VRs were winding up corrupted on the second pass. In further testing, sometimes the VRs would be too corrupt even to open.
So the concrete tip is: Don't redo VR objects while they're open. Maybe this is 'duh', but there are filetypes that can be rewritten while open in other apps: Preview has no problem with me overwriting open image files, e.g. And it's common to let AC have most of the screen area, so who knows what else is open in the background.
The meta tip is: If a weird problem crops up when you're rushing, it's very likely a normal problem that either wouldn't happen or wouldn't seem weird if you weren't under deadline pressure. When you see something weird, slow down, pay attention, and fall back on the good workflows you practiced back when the wolves weren't at the door.