I have a weird problem in my SharePoint 2007 environment on Intranet. There is a user added to a site collection who when logs in to the site slows down the intranet very much. Upon investigating it was found out that there is SQL Query runs every time the user logs in which blocks other processes. I then found out that the SQL query was pointing out to a hidden list on site collection called 'User Information List'. When I navigated to the list using SharePoint Manager I found out that for this user, there are multiple items created in the list with exactly the same name although the ID was different. All the other users have only one item each. I then open the same list on my site http://mysite/_catalogs/users/simple.aspx
and this doesn't show any item for this user at all.
Can anyone please tell me if this is the problem i.e. having multiple items for the same user in the list and if this is how to sort this our. I can't even delete the items from SharePoint Manager.