There is no option to delete all contacts from the phone, but NOT to delete them from the servers!!!!

that is the real issue!

and for that Nokia is to be blamed!!!

Sorry to hear you had problems. But I actually like it the way it is. I rarely remove just a part of the contact(yes that includes IMs and so on).

And reading warnings that are there usually helps. I REALLY REALLY REALLY wish users would read what's happening and if they DON'T understand what it is to ask first, hit OK second. If my mom can do it why not anyone else(and she actually is capable of doing updates to her xubuntu system without me being there)?

Seriously if it's not a hammer don't try to be smart about it. Learn what it is. We all needed to learn things to make them work.

If a device askes you: I'm gonna delete this here thingy from that there thingy?

If you have no clue what that means go ask first or read the manual.

it's not only an issue of smartness ... one uses these devices in a hurry ... more chances to make mistakes ... second: some have kids ... mine played with my phone and deleted stuff

same way you can reset timers without a password protection ....

there are tiny issues that were tottaly ignored ... i don't use the n900 as a phone now ....

yesterday i lost power, charged the phone and surprize: all sms's are gone

I think the delete all contacts should have the option to delete all also from the servers or just the ones in the phone

May I humbly suggest someone creates a n900 page by copying this one:
http://wiki.maemo.org/ManualBackupAndRestore

dude i understand your pain.. b4 i got the n900- i tried out the hd2. i deleted 1000 emails, which deleted of my server- the most current- i couldnt believe it...

I'm tech savvy. Can you explain how backing up your contacts would help in this situation?

It is my understanding that once contacts are deleted from the server as a side effect of deleting them from the phone, you cannot restore those contacts without getting personal confirmation from each person in the list, for each IM service - something that could take months or years, for those contacts who aren't frequently online.

Worse, with services which don't give every user unique names, it's impossible to restore from client-side data alone.

Even if you don't do anything wrong, how are you supposed to remove individual IM/Skype contacts from the phone that you want to remain connected with via other clients? According to this thread, apparently Maemo 5 does support selective client-side IM contacts, and there is a way to remove client-side contacts but it is stupidly convoluted: Remove your IM/Skype account entirely from the phone, and then reinstate it, adding back all the contacts you don't want to remove. That sounds like daft UI to me.

Please see my immediately preceding comment. Can you explain how backup & restore helps with the problem of mutually personally confirmed contacts removed from the IM/Skype servers? Because I'm not seeing how backup & restore solves that, although it is still a good idea of course.

Although I am not completely sure the "Nokia didn't make this program" warning is necessary every time I install something from the app manager, I do believe a "this will delete your contact completely from the IM server, are you sure you want to do that?" warning is in order.

Not because people is stupid, but because this feature behaves differently (in a destructive way) than what is expected from similar features elsewhere.

Edit: However, rereading the initial post, it seems that such an warning does indeed exist.

Ok, let's say someone is very careful, reads the manual (we'll ignore the non-existence of this part of the manual!) and checks the forums. They don"t click OK, because they are well informed, their English is good enough that they aren't confused by the slightly ambiguous wording of the pop-up message, they've read enough forum to understand that "delete all" behaves differently from "delete one" repeated, and they don't want to remove the mutually confirmed contact from the IM/Skype server. But they don't need that person on their N900 any more in their phone contact list.

So now what should they do?

It seems there is a lack of useful solution here...