Outlook rules keep getting duplicated and deleted

A highly irritating problem since I have to keep recreating and deleting rules.

I have about 20 mail rules that i built up and defined in Outlook (on web)

There are 3 others that run locally on the machine as they are for other POP/SMTP accounts.

Everything works, tested and functional.

Then I will suddenly see duplicate mails and upon checking, some of the rules, no pattern, will suddenly be duplicated. I see them this way on both the local machine and on Outlook Web Access.

So, i delete the duplicates to get things back to normal and everything works again.

Then a few days later I suddenly have no rules at all, or a subset, again, no pattern.

What on earth is going on?