AS, it looks like how this happens is that Bryce is writing the obp file and the computer crashes. Bryce can't finish writing the file, so the file's corrupt. I know that Bryce writes temp files(it also does that with animations, it used to "unexpectedly quit" for me every time it finished rendering one.). I also know that a PC crashes at the tip of a hat, and one of the main reasons are running mildly corrupt files, just corrupt enough that the computer can't tell that it's corrupt until it tries to run it. Everything leads to corrupt files, doesn't it? Regular defragging the HD would fix this(but so would buying a Mac!!).