Windows Vista's Hideous Wakeup Support
Throughout the beta, Deep Sleep in Windows Vista went great. It's the default option (so long as it's configured in the BIOS) when you click the shutdown button. It would put your computer in a low-power mode that recovered in a matter of 2 or 3 seconds, and didn't crash! But in the final version of Windows Vista, something is very, very majorly wrong.
When recovering from a hibernate: "Cannot find uxtheme.dll" appears whenever you attempt to run (almost) any program. No matter what you do, you can't even run Task Manager.
Failure to establish a network connection. Everything looks OK, but you can't connect to the internet.
Poor performance: though Task Manager will show normal CPU load, some of the drivers (they don't appear in TaskMan) will attempt to use 100% of the CPU, resulting in a very laggy PC.
For no reason, DWM just won't re-appear. This happens on ATi and nVidia, with or without the latest official drivers from the companies themselves.
BSOD on recovery. This is usually caused by the video drivers, and may or may not indicate something wrong with the kernel itself.
No sound. Vista goes mute. Nothing you can do about it, no way to revive it, you just have to restart and let the re-done sound-stack load-up the way it should.
All of the above errors and more occur randomly and make using hibernation down-right impossible (unless you're willing/eager to run System Recovery from the DVD!) and Deep Sleep a waste of time (seeing as you have to restart to "quick recover").