FCE 4 Suddenly Stops Recognizing Certain Files It Previously Recognized (File Error: Unknown File)

FCE 4 has suddenly stopped recognizing certain files that it has recognized without a problem for the past several years I’ve used the program. It won’t recognize 1920x1080 mp4, but it WILL recognize 1920x1080 mov and it WILL recognize 1080x720 mp4. All .h264 codec. Using AIC 1080x60i in FCE. It also won’t recognize .jpg or .tif. There was no software update that could have thrown this off. It was a working one day, not working the next kind of situation. Files play fine in QT. Reinstalled the program. I still get the same File Error: Unknown File. Any ideas?

Thank you!