Events seem to reappear in a crazy fashion in following months

I'm not quite sure how to give a technical description of this, but looking at my site makes it clear:-

http://www.likal.com/brockworth

Events for June are visible.

Click arrows to go to July, and all hell breaks loose. It seems that the system has taken all the June events and put them as all day every day events in July, and August etc.

For example if you look at the Plant Sale in any July day, you can see that the Node quite rightly says that it was one day event that started on 11 June at 2pm and closed later that afternoon. No way should it appear in July.

ALSO - if I am logged in as myself (i.e. full admin powers) the Event display is CORRECT! I'd suggest giving everyone admin grade, but that strikes me as a risky workaround.

HOWEVER

On my other site http://www.likal.com/theegg I don't seem to have the same problem.

Both sites are fundamentally the same - my PHP skills are too limited to do much to code and only really get used in static pages and blocks, and MySQL I leave well alone. They do however use different sets of non standard modules. Brockworth in particular uses Groups, Buddy lists, Notify and some others. The Egg is essentially a 100% Event driven product without any of the community/communications aspects. Could there be a conflict here?

Note - neither site is live yet, both are developmental phase, and I am waiting for The Egg to send me their icon to replace the drupal one.

I've flagged it is Critical because it really messes up the use of Event. Also I did a search and this bug had been reported previously by someone else in "How do I" back in May but no one had commented.