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
It's the intial load of your desktop by the OS, then a refresh. There could have been a process running in the background, and then terminated, which could have caused a refresh.