Driver installation in Vista SP1

So I set up my system from scratch some days ago - Vista SP1 RTM clean install. But suddenly, everytime I try to install a new device it keeps asking for the drivers over and over again - and doesn't find them! Among other things, I couldn't get my new printer (HP Color Laserjet 1600) to work or my U3 stick.

Funny thing is, it works when the devices are plugged in during a reboot. They're set up and installed, but Vista still then tries to install them again. But if I clicked that message away ("don't ask again") I could work with the devices.

And Vista wasn't very helpful: Although the problem reports and solutions had the right idea (sent me to download this Hotfix) it didn't work. "this update does not apply to your system". But as I said, the idea is right: The problem was the "infcache.1"-file, and the hotfix for KB940199 should have done nothing but to delete this file and recreate it.

I found a manual how to do this here, and it worked out without a problem.

So dear Microsoft - please make the hotfix work for SP1 RTM too.