Question: This morning I had to restart my windows 7 computer due to a security patch. As it was restarting, all the icons on the desktop appeared, then turned white and then the original images started reappearing. This is a common phenomenon after a restart and I've seen it other times (such as when I minimize all my windows). Can someone explain how this happens?

Answer: 
This seems like you may have a lot of start-up processes and services starting up all at the same time. This is both very CPU and memory-intensive. So when Explorer is initializing, it is sharing the load, and Explorer and the svchost services associated with it likely take up the most resources. A few things you could do:

1. Limit the number of startup programs (Start-->Search Programs and Files-->`msconfig`, or from cmd, type `msconfig`, or create a text file, type `msconfig`, and save it as `msconfig.bat` and use it for `msconfig` from now on).
2. limit the number of startup services (`msconfig`)
3. Set the CPU priority for less important processes (Task Manager, right click on the process)
4. Set the affinity for less important processes (multi-processor machines---this sets the number of cores/processors and which to allow the service to use---also rt click in Task Manager)

Adding more RAM may help a little, but remember: anything is as fast as the slowest link, so if the processor can't buffer more than what you add, you'd be wasting money
This is a common issue that you'll see with windows refreshing the desktop. You normally see this on slower machines that can't satisfy the resource requirements of "explorer.exe". While there are some minor fixes you can implement, they really don't do a whole lot to prevent this. 

Is this behavior something relatively new? When you first install windows, this refresh should be so fast that you can't perceive it. As you install software, additional startup processes, services, and desktop icons are added to your machine. Each one adds a few more cycles to the refresh time of your desktop. IT will eventually hit a point where you can now notice the refresh happening.

So how do you "fix" this? You have three options:

1) Use tools like MSCONFIG to limit the number of processes that start at launch. This frees up system resources for explorer to use to speed up the desktop load.

2) Reduce the number of icons on the desktop. This minor "fix" reduces the number of items explorer has to look at to refresh the page.

3) Upgrade your computer. Depending on the system you have, you might have low performing hardware that is slowing down your system. It can be hard to determine what to upgrade without knowing what is being slow.

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If you decide to take the upgrade route, here is my recommendation of the order to upgrade in.

1) Look at the amount of system memory you have. If it is less than 2GB, add memory. This is probably the cheapest and easiest thing you can do.

2) Purchase an SSD hard drive for your system. You can get 120GB for less than $200 nowadays and it make a big difference. Make sure to do your research before you buy. You will have to reinstall windows which might solve this problem outright.

3) CPU and Motherboard. If your CPU is more than 4 years old, you might think about an upgrade.

Good Luck