I had the same problem. After some trial and error I figured out that it was some .psd files that I had imported as a sequence.
I created a new premiere projectand imported the sequences from the old project that wouldn't open.
Then I used Photoshop to save the graphic as tiff files and reimported them into the project.
I replaced the .psd/sequences with the Tiff files and deleted the .psd/sequences from my project.
This totally solved the problem.
I know it's just a workaround but until this .psd import issue is fixed, it's a perfectly good one.
I hope this helps.