MXF files not importing properly

When I try to import some MXF files only some will work. Others I get an "Unsupported or corrupted file" error message. I have tried importing via through the opening import window, through the media library and by dragging and dropping. Had some success with all methods, but it doesn't make sense that some files load and some don't. They are all the same codecs and some that won't load now loaded a few months ago with no problem. 

Also worth mentioning that I had A LOT of problems initially with getting Premiere Pro to even open to begin with. It kept "not repsonding" on the splash screen and if I left it long enough (40 mins+) It would open, but lag and not import any MXF files whatsoever. I tried uninstalling and installing an older version, but I had the same issues. I then had trouble updating, then couldn't uninstall. I managed to install the new version again and it began opening without any problems, but still inconsistantly laods MXF files.