I receive this error every minute or less in many situations of heavy disk I/O. It happens under both FreeBSD 5.5 and 6.1. I've run a wide variety of versions of Parallels (I'm currently on build 5540) under both Tiger and Leopard. I reported this issue in the old forums a few times when I was still running Parallels 2 a little under a year ago, and several other users chimed in complaining of the same issue. Any word on what this is? It doesn't seem to corrupt data (thought I haven't examined things very closely) but it does stall disk I/O for a few seconds before the guest OS's kernel throws that message.