Office 2003 “save as” filenames w/spaces bug (%20)

In my Office 2003 installation (with all the latest updates), if I “save as” a file that has spaces in the filename and enter a drive letter in front of the filename without actually navigating to the drive first (d:\test this filename.doc) it replaces all the spaces with %20 characters. The result of the above example would be “d:\test%20this%20filename.doc”

It happens in Word, Excel, etc. Any fixes for this bug?