Thanks Tim, I downloaded and installed the latest but now get a different error.
The problem seems to occur after the current bets window has automatically refreshed e.g. after a bet is matched.
If I then click to sort by Placed, the error occurs.
If I click OK on the error, the display of bets is incomplete, showing only back or only lay bets, until I close the current bets window and re-open it.
update: the error only occurs on a slow vista laptop, on win7 pc no problem