You can try changing the location of the project and the files.
Or you can also try creating a new sequence according to the project and import the project with problems.
As a general piece of advice - never update to new versions while midway during a project. Or - at least keep the older versions active on your system and make sure you have a backup project available so you can continue editing in the previous version should you run into troubles with the new(er) version.
As for new versions - make sure you update your GPU drivers from the vendor website (e.g. nVidia), not through your system's OS and that you have all the necessary codecs available and updated.
You may try and set up a new project and then import the existing project in that one.
Hope this helps.