[help please] USB- and Laptop-Keyboard unresponsive on Bootup

Hi,

I've got a problem when booting up my Vista Business.

After I've deleted my old Windows XP partition to make my Vista Partition bigger (GParted), and after repairing the Boot Record (Vista DVD) to make Vista boot again (seemed to be the standard procedure i found) I tried to boot up my System. I didn't change anything in the system itself.
After I reached the Logon-Screen I could not use my Keyboards (neither my Notebook Keyboard, nor the USB-Keyboard I attached). I tried the Vista-DVD-Recovery again, I tried Safe Mode, I tried turning on/off legacy-Drivers, I pretty much tried every option in the Vista Advanced Bootup Menu (restore previous version, safe mode, with/without networking, debugging) but none of those helped. I tried different USB-Ports and also I tried to use the On-Screen-Keyboard (which didn't load up, maybe I uninstalled it a long time ago, I don't remember). The keyboard itself is getting power from the USB-Port as some lights are on, yet it's non responsive (e.g. pressing num lock button)

I can't find anything that I could still do there and I really want to avoid having to reinstall the system.

cheers,
meta