This effects 2014 QB Desktop Pro as well. Win 7 computer that has NOT been updated in the last 6 weeks, fails to load QB, 3371 error.

Only workaround found:

• Delete the file as noted: EntitlementDataStore.ecml.
• Open QB again, login. Should get back into your company file
• DO NOT REGISTER at this time, choose later (it won't matter if you register again, it won't stick)
• DO NOT CLOSE the program - just choose "close company/logoff" found in the "File" menu. This will allow you to log back into your company file without it failing again.

If you close the program, you will have to rinse and repeat.

Intuit - fix this now, it is unacceptable.