Thanks guys. Maybe I didn't express my thoughts clearly enough, but I did not lose any coins, yet. I was just wondering why people lose coins if all can be restored by remembering the private key. BTW I think the safest place to store a private key is in your own brain; of course not in the form of a completely random string of characters, albeit as a quite unique sentence, which you encrypt and hash on a stand alone (offline) computer. The FBI confiscated BTC170,000, now why wouldn't these 'criminals' (or their partners) have moved these coins to another wallet, or were the FBI-agents smart enough to do this themselves already. Hmm, just thinking out loud again ...