I appear to have cracked the problem! Although I'm not able to use the existing calendar, WLM has allowed me to start a NEW calendar (via button top left of screen), and it seems to work perfectly. I just have to re-enter all my birthdays, appointments etc manually. Quite happy to do that - at least I now have a usable calendar conveniently placed alongside my email program. Thanks for all your advice guys - hopefully I am now sorted.
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