The only other idea I can suggest is this:
First, make a copy of your data file. Use Quicken (File > File Operations > Copy...), to make a copy of your data file. Quicken will do some file cleanup whereas the Windows copy will make a bit-by-bit copy.
Then validate the copy of the data file you just made: File > File Operations > Validate and Repair... Make sure you check the Validate file checkbox.
If that doesn't work (and I have my doubts), your best bet would then be to contact Quicken Support (see the links at the bottom of the webpage).