This may be the same issue as discussed here:
http://www.bisque.com/sc/forums/t/24398.aspx
and here:
https://groups.google.com/forum/#!topic/open-phd-guiding/5YKW5-J4Grk
and toward the end of this SGP thread:
It was found by Chris Woodhouse (Buzz) and appears to be a bug in the latest TSX (8805) build.