KB 977346 - Welcome screen may be displayed for 30 seconds during the logon process after you set a solid color as the desktop background in Windows 7 or Server 2008 R2

This definitely the strangest bug I've ever encountered with Windows 7 but I have experienced it on numerous systems because on any system that I have control over, I typically set my background to black. No wallpaper. No pattern. Just black. I also do this on Windows 2008 R2.

I would typically hear some applications loading in my tray and "ding" me for UAC access to hardware, but would still be sitting at the Welcome screen.

I originally wrote it off as a fluke when it first happened but after installing the hot fix, there is a definitely a difference in behavior.

Consider the following scenario:

You have a computer that is running Windows 7 or Windows Server 2008 R2.
You set a solid color as the desktop background.
The Desktop Window Manager Session Manager service is running.
You log on to the computer locally.

In this scenario, the Welcome screen is displayed for 30 seconds during the logon process.

This issue does not occur when one or more of the following conditions are true:
You log on to the computer by using Remote Desktop Connection.
The Desktop Window Manager Session Manager service is stopped or is disabled.
You set an image file as the desktop background.

You can read about the issue and download the fix from here.