Premiere elements suddenly not accepting M4a

About a month ago I made a video in mp4. I recently noticed an error and want to correct it before I burn it to DVD, so went to edit the original prel timeline and make a new mp4.
But an M4a music clip I was used for the video now doesn't work. Re-importing it gives a 'generic error'.
I have found that NONE of my M4a's will now import.
This waas never a problem before. I don't want to have to convert all my M4a's [hundreds] to mp3!

What has changed?
I hate updates.