Ajitjha, I tried to repair the installation but it was the same. When I tried the uninstall and reinstall, it finally worked. I can now launch a full system scan from the client. I'm happy that we found a way to make it work but I can't imagine reinstalling the client to the other PCs with the same issue. I'm still trying to find out which kind if installation is bad and which is good.
I executed the setup.exe from a shared folder on the server, this one looks good. I have a feeling that using Symantec's Deployment and Migration Wizard is not good. I'll test again and let you guys know. Thanks for all the help. =)
This is a temporary solution but not the best. The best would be to fix the issue without reinstalling. If you guys know how to do it, please share it with me. Thanks again.