After unlocking officially my iphone 3GS OS 4.3 applications cannot be started

Hello

In order to change my provider, i asked to Bouygues France, to unlock my phone (not jailbreak).

I respected the process and obtained the apple right message in Itunes, it was correctly unlocked. I tested another SIM card, it was ok.

All was ok since my iphone powered down.

Then, i cannot launch the downloaded applications, i can only  launch the integrated ones.

I tried some tricks like :

- reset iphone

- uninstall/reinstall app

- app update

- authorize pc on itunes

My last backup is very old. Should i restore it? If I restore, will the phone go back to the "locked" state?

Any other trick ? Someone encountered the same issue?

I'm very disappointed with this issue, i thought that unlocking an iphone was really without risk!!

Thanks for your help

BR

bp