Windows Vista desktop keeps shifting icons around

I do not know if this is a Vista thing but simply a Windows anomally.

Every once in a while the icons on my desktop go askew and rearrange themselves.
I do not know if this happens when I run a cleaning or defraging action or an update or ???

When this happens it is irritating because I compartmentalize my desktop icons in categories of functions.

How can I stop the computer from rearranging my icons at will???

 

How to stop Vista from rearranging my icons from here, and other choices too.

kind regards,

 

Thank you Tallin.
I downloaded the Retina software and will figure it out over the next few times I have free for computer time.
I will close this thread and I hope others will benefit from your wisdom and expertise contained in this post at other times down the line.
A Blakston