WampServer

I had installed ver. 2.2E 32bit locally on win xp with PHP 5.3.13. I worked fine for over a year.
Since I needed PHP 5.4+, I read on the wampserver site that I could just install the same version over the existing one, but with PHP 5.4.3 and be able to swap PHP versions at will.
The installation went fine, but after that I get the error:
Error establishing a database connection
from ANY of my wordpress installations that worked fine up to that point.
Also, ANY other installation of any CMS etc that needs access to MySQL gives error.
The strange parts :
1) Wampserver and the services go off line and on line with no problem.
2) I can acceess localhost and see PHP settings
3) phpMyAdmin runs OK and I can see all my databases
4) I can access MySQl console

5) trying to switch from PHP 5.3.13 to 5.4.3 gives me errors about mbstring and mysql being compiled with an older API than PHP 5.4.3, so I guess MySQL modules PDO etc are not loaded WITH PHP 5.4.3. But they are when switching to 5.1.13 and then I have the above mentioned problems.

Any help welcome

Petros

PS: After dabbling a little I found out it had trashed my db users. After I recreated them everything seems OK, BUT point 5 remains : how can I switch from PHP 5.1.13 to PHP 5.4.3 and have MySQL extensions loaded?

There is a dependancy where if you are using php_exif it is dependant on php_mbstring.
However the extensions are entered in alphabetical order in php ini, so you would need to move exif after mbstring.

This is just a guess, dont beat me up if its totally irrelevant.