Closing Files after Unload?

I just download a trial copy of a mem viewer etc called 'TaskInfo2000'. It displays a lot of information about each app running. One of the tabs displays what it calls 'Files' and shows each file that is opened for a particular app. My ? is that I can see several files open for a particular form but... when I close that form, not all of them close? I have set all of my objects and my form to nothing on close and it still shows that some of them are opened? The ones that are opened, refer to controls that have a data source. I have closed all data sources and set to nothing but they still show that the files are open? Here are a couple of files that are still opened 'msvbvm60.dll', 'ssdw3bo.ocx'. The first one is a vb file and the second one is a Sheridan control? I also am using a ULTRAGRID control and that file shows that it is closing and it is also a control that has a data source? The app runs good but it doesn't show that all of the memory is restored after I close forms and have only the main menu opened? I know that this has been brought up in this forum a lot and I have read a lot of the posts. I just wondered if anyone knew why these files are still open and if they could be part of the reason my app doesn't seem to free memory when forms are unloaded?