I have never seen a 4gb SD (non-HC) card, my understanding was that the maximum is 2gb. Anyway, give it a shot at let us know what happens.
They probably discovered your clippings file is corrupted from the logs. You can copy your clippings file off the Kindle, right? It should be drag n' drop. Try a select-all and paste it into a new text document in Notepad or a similar text-only editor.
It was also my understanding that the Kindle uses no power unless you flip a page. That must not be the case though, because I left it on for about 16 hours and when I picked it up again it was flat-out dead. The battery indicated about 20% left when I set it down. I suspect the battery meter isn't very accurate.