If you have not done so already, I would try opening Quicken in "Silent Mode." This will open the Quicken program without opening a data file.
To open in silent mode, hold down the Ctrl button and double click the Quicken icon on the desktop, continuing holding down Ctrl until Quicken opens to a blank gray screen with only the File & Help menus in the top left corner.
Then navigate to File > New, to open a blank new file. If you are successful in doing so, I would then try to sign out and sign back in.
Please let me know how it goes!
-Quicken Tyka