One of my post popular blog posts deals with problems I was having with the stability of Windows Vista. I had major problems hibernation and sleep modes on my Dell PC. My PC never reliably went to sleep or hibernation and crashed either during going to sleep or when waking up. A lot of other people encountered similar problems. This blog post has 66 comments so far.
No driver update or Windows update solved my problem until October 9, 2007.
Around that time Microsoft released a set of reliability updates that are going to be part of SP1. There are supposedly also going to show up in Windows Update, but I manually downloaded and installed them ahead of time. Note that I am not running the beta of SP1.
If you encounter similar problems with Windows Vista, I highly recommend that you install these updates as well (if you haven't got them through auto update yet):
This update resolves some compatibility and reliability issues in Windows Vista. By applying this update, you can achieve better reliability and hardware compatibility in various scenarios.
This update resolves some reliability issues in the USB core components on the Windows Vista operating system.