using Distrib 5.0.45 on ubuntu 7.04, mysql was installed via adept manager.
I'm getting many error messages on the type:

Can't find file: './mysql/(database_name).frm' for numerous databases.

The mysql database was installed automatically during installation, and
I'm getting them for ./mysql/time_zone_name.frm.
Also:
I'm getting these type of messages from databases that were installed
manually via mysq and a script file.
And:
I'm getting them from databases installed by directly copying to
/var/lib/mysql/(database name) from other machines.

In each case, I find that the ownership is set at mysql:mysql and
permissions at 660.

I'd like to resolve this problem ASAP as it is driving me crazy :-), so
any would be appreciated.

thanks
tim