Users can't be added in a project

Users can't be added in a project

Hi,

Since sometime, i am having a weird issue.

1. For a project i add couple of users
2. The users are shown in the user list.
3. After sometime / some days the users no longer show up in the user list for the project.
4. When trying to add the users again, i get error message "User was already added to this project"

Thanks,
Rajiv