Error# C00D1199 in Windows Media Player

hi! i've been downloading AVI files from my Canon
Powershot Camera to my PC. i don't know what happened
but i suddenly have a problem opening the files i used to
open. i get a message that the media player doesn't read
the file, which is totally weird since i was just able to
play the file a week ago.

the error code is stated in the subject box.

does anyone know how i could fix this problem? would
really appreciate it, thanks!!!