I have a large workbook that has a considerable amount of Conditional
Formatting (CF) that works fine in 2003. When I run it in 2007 Compatibility
mode I find that some, not all, of the CFs don't work first time. It goes
like this:

Cell has CF to change its colour if a second cell changes to TRUE. This is
triggered by the User ticking a control. This is repeated many times down the
page with each event independent of the others.

In 2007 when the control box is ticked sometimes it works fine but on other
occasions the box accepts the tick but nothing happens. If a number is
entered into the offending cell it changes colour, then if the control is
unticked and ticked again it works fine and continues to do so if the control
is ticked and unticked . If this is done for event 1 it seems to remedy event
2 and onwards. Whether the event works or not seems to be fairly random
initially but entering the number once seems to sort out the whole sheet.

This seems like a bug, but how do I remedy it?