Single vs. Multiple File Uploads

Hi,
I have an application that combines single & multiple file uploads. In some cases I want to allow users to upload several files. In others, when I know the files may be large -i.e., audio or video files- I want to restrict their uploads to only 1 file. I want to know if it is possible to have both things working together.

My application works if I only do one or the other. If I try to switch from Multiple to single uploads, or vice versa, I get this error:

[COLOR=DarkOrange]Error: Error #2041: Only one file browsing session may be performed at a time.[/COLOR]

How can I close/delete/eliminate any previously opened browsing session?

Thanks so much.