That error actually means the database of Picasa is corrupted and broken. You will have to rebuild it properly before you can use it again.
Go to Windows + R and type
%LocalAppData%\Google\. You'll have additional folders inside Picasa, just locate the db3 folder and delete everything except the following files:
Launch Picasa and wait for it to re-index the files. It could take 2 hours for 10.000 pictures.