Annoying brackets in IE temporary filenames - looking for a magic fix...

Is anyone aware of a way via headers, or just plain voodoo, that will make a temporary file that IE uses not use the square brackets? i.e. foo[1].xls Here is my scenario: I have files being served out of a database from blob fields for an internal site. We seem to have this one picky program that does not like files served this way, and complains. If I visit my local IE cache directory, and remove the square brackets from the filename, I can open it just fine. If I put them back, I can no longer open the file. We need our users for convenience to be able to open these in the browser directly, instead of downloading the file, then browsing it it's location, and then opening it. I have been scouring google, and newsgroups all afternoon, and playing with different headers, etc. and still cannot seem to accomplish this... Any help would be greatly appreciated! Thanks!