Hi, I thought this might be of interest to a few people here (and may help some). After installing SP1 on Vista 64 today, and after logging in, I was greeted with a black screen and my cursor. Nothing else would work! No explorer, no CTRL+ALT+DEL - nothing! After some time of fooling around and not having much luck, I booted in safe mode and uninstalled Eset Smart Security, and rebooted normally. After logging on this time, I was greeted with a dialog after a few moments that said something like "Vista SP1 installed successfully". I have now reinstalled ESS on my laptop and all seems to work fine now. I hope this helps someone else out there, and saves them quite some grief! (I'm guessing that ESS was somehow blocking the final part of the service pack update, or Vista wasn't liking something that ESS was doing).