"check your destination files, and make sure they haven't been moved, also you may want to make sure your hard drive has enough free diskspace"
i got a similar problem and decided to un-install it and reinstall it to see if that changed anything - some of the things i was trying to save were very small files, so if there is a limit then ... err well the file was about even less than 3mb. also just to make sure i try do a different movie still keeping the orginal files in place same error.
i go to download.com find it has movie maker download that and installs good but then when i try run it it says something along the lines of "windows is searching for 'moviemk.exe"
ok uninstall and try reinstall but again same problem occurs. i take it that the download may be missing some files?
anyway i have service pack 2 already and am also running firefox - i also looked for downloads for "windows movie maker" and results were thin lol
any suggestions? either as to what to do or other possible options where to download movie maker without being pointed in the direction of service pack 2 or download.com lol