Looks like many possible reasons causes this problem
It didnt work for me ....!!!!
then, I just gave up and used Odin only to update my SGS2 (GT-I9100) with new firmware (4.0.4) ...
For some reason, my phone was reset to factory defaults...!!!
Then Guess what happened ??!!
Kies worked normally and been able to connect normally and backup my phone ..
Then, happy with this, I continued installing my applications on phone ....
I configured the "Microsoft Exchange Activesync" .....
I connected my phone again to PC, Kies stopped working again ...with same error message ... (searching for preconfigured folders).
Then, I could analyse it and find the reason ...
ITS DUE TO ADDITIONAL SECURITY RESTRICTIONS THAT ARE INFORCED BY ActiveSync ADMIN.
When I installed ActiveSync, it tells that I must put screen password and let remote administrator manage my security.
it seems that there is a "bug" in Kies with this and hope I can report the issue to Samsung.
I tested my assumption by removing ActiveSync account totaly and in fact i connected to Kies normally ...!!!
Please make sure that non of your applications is puuting additional security on your phone.