As nothing had changed in my configuration except upgrading to windows 7 32 bit version, I had been suspecting this might be causing my issue.
I read the Nov 29 post regarding logfiles and did some further testing this AM.
It appears my suspicion was correct.
As nearly as I can tell the file UDReport in the directory c:\users\myname\appdata\locallow\ is the cause of the problem. It appears it can not be overwritten, hence every time I opened it in Excel I saw a 3 month old log.
If I save the log file to a local file and open it with Excel I can see the log was cleared and all current events.
For now I can get around the problem but thought you developers would like to know and maybe can fix it...
I saw the comments about upgrading to 2.7.7 from 2.7.0 and am not sure if that might resolve it?
Also I have never tried to upgrade the ISY remotely and am not sure if it can be done. I have no access to the ISY until April so have fears of doing that