For people that'd have similar problems, I do want to share my experience:
0. I never had a Network Unlock problem 'til yesterday when I finished to install XXLS7 SVA 2.1 ROM for N7000
1. I tried to use Galaxy_S Unlock proposed by dr.ketan on post #4, it did not work for me at all: it said it's unlocked, but still Network Unlock Code asked
2. Then I found GalaxSim Unlock from Play Store: this one worked flawlessly on first try! Till now, no more Network Unlock Code is shown nor asked even after reboots. It is perfect! and worked for me like a charm, and many others when we regard comments. The only bad thing is the €2 fee. I was so despair that I paid for that and... no regret!