Why did Windows 7, for a few months, log on slower if you have a solid color background?

Time for another story from Raymond Chen, about why, in Windows 7, logging in took 30 seconds if you had set a solid colour as your background. Windows 7’s logon system needs to wait for a number of tasks to be completed, like creating the taskbar, populating the desktop with icons, and setting the background. If all of those tasks are completed or 30 seconds have passed, the welcome screen goes away.

As you can guess by the initial report mentioning having to wait for 30 seconds, one of the tasks that need to be completed isn’t reporting in, so the welcome screen is displayed for the full 30 seconds. In the case of this bug, that task is obviously setting the background.

The code to report that the wallpaper is ready was inside the wallpaper bitmap code, which means that if you don’t have a wallpaper bitmap, the report is never made, and the logon system waits in vain for a report that will never arrive.
↫ Raymond Chen

It turns out that people who enabled the setting the hide desktop icons were experiencing the same delay, and that, too, was caused by the lack of a report from, in this case, the desktop icons. Interestingly, it seems especially settings changed through group policies can cause issues like this.

Group policies are susceptible to this problem because they tend to be bolted on after the main code is written. When you have to add a group policy, you find the code that does the thing, and you put a giant “if policy allows” around it.

[…]

Oops, the scope of the “if” block extended past the report call, so if the policy is enabled, the icons are never reported as ready, and the logon system stays on the Welcome screen for the full 30 seconds.
↫ Raymond Chen

These issues were fixed very quickly after the release of Windows 7, and they disappear from the radar within a few months after the release of everyone’s favourite Windows version.