A better alternative may be to have the user choose a folder
(Folder Browser Dialog)[
^] and then save the files using set names.
Your names could be hard coded or configurable through the application or maybe just an external XML.
I think your users whould be much happier.
Also this tends to make more sence in bulk saves as the files are actually tied together so having them all in a folder with consitent naming to a previous save makes sense IMO.