To add to this, the best way to get some log output in case of crashes is opening a Windows Command Prompt and starting Picard from there with:
"C:\Program Files\MusicBrainz Picard\picard.exe" -d
This will print debugging output directly to the command prompt window with hopefully helpful information.
Yes, in case you upgraded from Picard 1.4 you should follow @IvanDobsky’s advise of completely uninstalling the software and reinstalling.
Just to clarify: The issue in this case was not the path, it was left over files from previous installation. While you are supposed to install 64bit applications to “Program Files” and 32 bit applications to “Program Files (x86)” there is otherwise no magic behind these paths, your software will just run fine from either path (or any other you install it to).