Notifications can't be deleted

I have discovered a strange problem - I haven't seen any others having this issue, but maybe someone in here can help?

If I select to be notified whenever one of my friends add something to the site, then I do get a message - but this message is very sticky, it remains unread and impossiple to delete.

I havent touched the notifications plugin, so everything is standard 1.5 code.

Any ideas on what's causing this?

Update: admin can delete notifications, but nobody else..