Import Video File Compatibility

I have been using Cubase 6.0.5 and have experienced intermittent file conflicts when trying to import video. I’ve imported an MP4 video fine one day and the next day Cubase says it’s an unrecognized file format even using the same
video. I’ve even imported video into a project, video worked fine, saved the project, re-opened the project the next day and Cubase no longer recognizes the video file and says it’s an invalid format.

Also, I’ve had problems with Cubase crashing when shutting down if I don’t close out the video preview window first. If I tried to close Cubase with the video window visible, the program would freeze.

I just updated to version 6.0.7. Have the issues I’ve described been noticed by anyone else? Have they been addressed in the updates? (I didn’t see them addressed in the version history). Does anyone know the most reliable video format to use with Cubase? I’ve been using the recommended Quicktime and MP4 formats and still having problems.