Well I don't know why it would through up that error, it is a bit strange as it is a windows file system error and not an avast specific error. So I don't know if there is a particular problem with the BIT??.tmp files that are in these Software Distribution, Downloaded files, but for some reason it appears to be trying to look further into the file (the |>_sfx_*. part) when it encounters the end of file.
Personally I don't believe it is something to be overly concerned about.
Have you been updating video card drivers, etc. (my guestimate on the _sfx_ reference) ?