We have experienced the exact same problem, plus a another regarding two unrelated files becoming corrupt and all data being mysteriously deleted to 0kb, and therefore the file rendered utterly useless. We currently run Vectorworks 11.5.0 on a network of three apple macs all running on MacOs 10.4.4. I read in another posting that network backups might be a factor. We back up nightly to (alternating each week) 250GB external hard drives over the network, but thus far have used up only about 62GB of capacity. The other possible cause is 'legacy data' becoming corrupted, as in all cases these corrupted files have been translated from VW 9 or even MiniCad 7. As we are a very small office it is impractical for us to redraw every old file new in VW11. Has anyone got any suggestions please? At present our only failsafe is to deposit a duplicate of each new drawing into a separate VW 'safekeeping' folder just in case the original gets corrupted. We are very disappointed and are really regretting the upgrade to version 11 as it has caused us so much trouble with data losses. It doesn't look as if VW12 is any better either....
