Awareness view in column generates error

Lotus Domino Server 6.5.2

NSF: addressbook

View: _People

Additional Column: ST Awareness

When opening the view within the browser, the following message is displayed:

HTTP Web Server: Corrupt Data Exception [/names.nsf/People?OpenView]

When deleting the column, it works fine (well, the view worked with 6.5 and 6.5.1).

Any idea? Thanks in advance.