Windows 7 supports a wide range of selecting solid color background, this approach has brought an unexpected “adverse impact”. It is likely to cause every time you start Windows 7 , a 30 seconds delay is added when the system starts.
This is not an isolated phenomenon, but this exists in Windows 7 and Windows Server 2008 R2 both as a bug, on this issue there is a KB article on it: KB Article
Avoiding this bug is also very simple, as long as you do not use a solid color background, you will not face it. But if you have to do with such a solid color background, and do not want to spend 30 seconds extra startup time, Microsoft has two recommendations:
1. First create an image in any picture editing software and then fill it with the solid color you want it, and finally this picture set wallpaper on it.Then set to wallpaper with “tiling” method on it.
2. Modify the registry, using this trick, you can directly use the default color picking method for solid background in Windows 7.
Navigate to: HKEY_LOCAL_ Machine >SOFTWARE >Microsoft >Windows >CurrentVersion >Policies >System;
Double-click DelayedDesktopSwitchTimeout registry entry in the Value data box, type 5, and then OK to exit the Registry Editor.
If it does not exist, right click>New>Create a 32 bit DWORD value, name it DelayedDesktopSwitchTimeout.
Close the registry; you will not face the problem any more.