Strange error in eventviewer

[Paul van Brenk [467934]]

Allthough everything appears to be working as it should, except for the
occasional restart of the aspnet wp due to memory exhaution. I get the
followin warning in my eventlogs, about every 20 seconds:

Error "Attribute names must be unique." occurred while parsing the User
policy level. The default policy level was used instead.

I have no idea, what could have triggered this, ( I don't know when it
started, the older events are overwritten in the eventlogs :( ), if you have
suggestion?

Paul