Exactly the same problem as the original poster.
Was running 1.7.5 with no modifications or 3rd party plugins at all. 1.7.5 was running fine.
Also didn't have an og_plugins table in the database. But now since upgrading to version 2, the log file just contains tons of references to this table that doesn't exist...
Session "default" started at 2012-04-02T10:11:18+0000
#1 DEBUG: SQL ERROR: Query failed with message 'Table 'db_name.og_plugins' doesn't exist' - SELECT * FROM `og_plugins` WHERE is_installed = 1 AND is_activated = 1
#2 FATAL: exception 'DBQueryError' with message 'Query failed with message 'Table 'db_name.og_plugins' doesn't exist'' in /var/www/vhosts/domain.co.uk/subdomains/projectx/httpdocs/environment/library/database/adapters/AbstractDBAdapter.class.php:386
Stack trace:
#0 /var/www/vhosts/domain.co.uk/subdomains/projectx/httpdocs/environment/library/database/adapters/AbstractDBAdapter.class.php(304): AbstractDBAdapter->prepareAndExecute('SELECT * FROM `...', NULL)
#1 /var/www/vhosts/domain.co.uk/subdomains/projectx/httpdocs/environment/library/database/DB.class.php(213): AbstractDBAdapter->executeAll('SELECT * FROM `...', NULL)
#2 /var/www/vhosts/domain.co.uk/subdomains/projectx/httpdocs/environment/classes/dataaccess/DataManager.class.php(277): DB::executeAll('SELECT * FROM `...')
#3 /var/www/vhosts/domain.co.uk/subdomains/projectx/httpdocs/application/models/plugins/base/BasePlugins.class.php(111): DataManager->find(Array)
#4 /var/www/vhosts/domain.co.uk/subdomains/projectx/httpdocs/environment/classes/dataaccess/DataManager.class.php(315): BasePlugins->find(Array)
#5 /var/www/vhosts/domain.co.uk/subdomains/projectx/httpdocs/application/models/plugins/base/BasePlugins.class.php(126): DataManager->findAll(Array)
#6 /var/www/vhosts/domain.co.uk/subdomains/projectx/httpdocs/application/models/plugins/Plugins.class.php(39): BasePlugins->findAll(Array)
#7 /var/www/vhosts/domain.co.uk/subdomains/projectx/httpdocs/environment/classes/hook/Hook.class.php(30): Plugins->getActive()
#8 /var/www/vhosts/domain.co.uk/subdomains/projectx/httpdocs/application/application.php(16): Hook::init()
#9 /var/www/vhosts/domain.co.uk/subdomains/projectx/httpdocs/init.php(151): require_once('/var/www/vhosts...')
#10 /var/www/vhosts/domain.co.uk/subdomains/projectx/httpdocs/index.php(9): require('/var/www/vhosts...')
#11 {main}
Time since start: 0.0075869560241699 seconds
The error given at public/upgrade script was identical to the one in the OP...
Warning: mysql_fetch_object(): supplied argument is not a valid MySQL result resource in /var/www/vhosts/domain.co.uk/subdomains/projectx/httpdocs/public/upgrade/library/functions.php on line 192
(All other steps were the same as OP too).
I then couldn't load the complete_migration.php script (just a blank white page), I can't load any other pages either - just a blank white page. I changed the table prefix in config.php but made no difference.
Really frustrating as I've spent three hours trying to upgrade this today and now I'm going to have to give up and roll back to 1.7.5 as we require feng running for daily operations.
As others have said, there is clearly an issue with the upgrade process you have provided, it shouldn't be referencing a table that never existed in the first place after it has created a load of new tables with the fo_ prefix - switching on debugging doesn't even output the problem either.
Can an admin/dev provide a fix for this please?