[mono]root@ubuntu:/var/www# vi /etc/php5/apache2/php.ini
(убрал строчки extension=mysql.so и extension_dir=...)
root@ubuntu:/var/www# updatedb
root@ubuntu:/var/www# /etc/init.d/apache2 stop
* Stopping web server apache2 ... waiting . [ OK ]
root@ubuntu:/var/www# apt-get remove php5-mysql
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
php5-mysql
0 upgraded, 0 newly installed, 1 to remove and 6 not upgraded.
After this operation, 246kB disk space will be freed.
Do you want to continue [Y/n]? y
(Reading database ... 30236 files and directories currently installed.)
Removing php5-mysql ...
root@ubuntu:/var/www# aptitude install php5-mysql
Reading package lists... Done
Building dependency tree
Reading state information... Done
Reading extended state information
Initializing package states... Done
Writing extended state information... Done
The following NEW packages will be installed:
php5-mysql
0 packages upgraded, 1 newly installed, 0 to remove and 6 not upgraded.
Need to get 0B/65.9kB of archives. After unpacking 246kB will be used.
Writing extended state information... Done
Selecting previously deselected package php5-mysql.
(Reading database ... 30232 files and directories currently installed.)
Unpacking php5-mysql (from .../php5-mysql_5.2.6.dfsg.1-3ubuntu4.5_i386.deb) ...
Setting up php5-mysql (5.2.6.dfsg.1-3ubuntu4.5) ...
Reading package lists... Done
Building dependency tree
Reading state information... Done
Reading extended state information
Initializing package states... Done
Writing extended state information... Done
root@ubuntu:/var/www# /etc/init.d/apache2 start
* Starting web server apache2 [ OK ]
root@ubuntu:/var/www#[/mono]
, и видимо была как раз в ини-фаилах. после этого PMA заработал, и пхп перестал ругаться на неопознанную функцию mysql_connect() 
спасибо за участие)