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I've made clean installation of Windows 2-3 times since I've entered the passwords last time.
I hope the investigation of this case can improve the Bitcoin world and can prevent such incidents in future
The isn't a bitcoin issue, this is a computer security issue. If you can't secure the computer, nothing that the bitcoin developers do will help stop it.
If you can't secure Windows, use Linux or OS X or any number of other OSs. And use them ONLY offline. Or use a paper wallet. Or a hardware wallet.
Sorry for the loss.