Error: CblockFile::openBlock err=11, thumbs_0.db
When starting Picasa, you may see the above error message. That is because the Picasa database may have become corrupted causing Picasa the database to be out of sync. The solution is to rebuild the Picasa database.
See directions here: Rebuild Picasa Database
Another solution to try:
In Picasa, click View, then "Small Thumbnails"
Close Picasa, then restart it
Click View, then "Normal thumbnails"