Upgrade to Gallery 2.2.6.1 gives 'Gallery File Integrity' warning - afterwards Gallery no longer works

Hi,

I upgraded my Ubuntu 8.04 server to 8.10. This included an update for Gallery2 from 2.2.4-1ubuntu0.1 to 2.2.6-1.

After the upgrade a visit to my gallery homepage took me to the upgrade page (which I first had to chmod 755). All looked well except for the 'Gallery File Integrity': 205 missing files complaints (see attached). Stupid as I was I just pressed 'Continue to Step 3' anyway and continued the upgrade as if all were fine.

My Gallery2 site now doesn't work anymore. If I visit main.php I only get a white screen (and funnily on another browser a 500 server error message).

Amazingly I was smart enough to follow the advice to make a backup of the database which I did.

Could anyone share some pointer to how to solve this:
- Shall I reinstall? (using apt-get or ..?)
- Better to put the database backup back? (how?)

Thanks in advance,

Otto