[Q] How to go from Cyanogenmod 10.1 to Stock rom?

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http://forum.xda-developers.com – Hey guys. I own the Sony Ericsson Xperia Arc S . I have rooted it and installed cyanogenmod 10.1. Now the cyanogenmod is nice but it still has a lot of bugs and it lacks in a lot of aspects in comparison to the stock rom. Now i would like to go back to the stock rom which was ICS 4.0.4 Is it possible to downgrade from 4.2 to 4.0.4 ? if yes then a complete tutorial would be highly appreciated for my problem . Thanks in advance. (HowTos)