I'm was having a similar problem to Mauro. MySQL was working fine in
command mode.
My configuration is:
Developer mode running a non-transactional database, i.e., I don't
want Inno-DB involved, so I uncommented the php_mysql.dll line in the
Apache httpd.conf file.
What I wound up trying was copying libmySQL.dll into my Apache2\bin
directory. Then, everything worked fine.
The really irritating part was that ALL of the error messages made it
appear that the problem is with the php_mysql.dll file and it appeared
that Apache couldn't find the php_mysql.dll file. In all the error
messages I have received, NONE of them referred to the libmySQL.dll
file.
HTH.
virginia