Is the model checked out when you do this and checked in with the drawing? Is the BOM in the drawing linked to the same configuration as the view? Is the view linked to the BOM? Are the parts in the BOM (not hidden)? When you hover the mouse cursor over the ?, what is the message?
Last resort: you could switch from item no. to text for the balloons and try.
Are the parts still in the stack when the '?' is showing? i.e. if you open the assembly are they there?
Is PDM set to manage the toolbox? Are your system option set to use the vaulted toolbox or the one on your C drive? What about the checkers options?