After hours of searching, it appears that in spite of all of the posts that suggest this is an upgrade
issue that it really is a PHP support issue. I'm using PHP 4.3.9, so maybe PHP 5.0 has addressed
this, but I haven't had time to wade into that.
So I settled for using the old 16-byte password encryption.
In my.ini file in the mySQL directory (e.g., C:\Program Files\MySQL\my.ini), add the following :
#Use old password encryption method
old_passwords
Save and close the file. Where you add these lines really doesn’t seem to matter, but most of what
I read said to put them in the [mysqld] section.
If you use phpAdmin there are further issues. See mglatts's post on 7 Jan 2005 for discussion
of those at
http://forums.mysql.com/read.php?11,6400,10611#msg-10611.