Multiple placements in Google

[jbcobbs]

Why is it that my website changes specific positions throughout the day. I go from #10 to #11 to #16 to #36 randomly throughout the day. Furthermore sometimes my site description comes on www.mysite.com and sometimes it comes up mysite.com. Either way, I could use some assistance.
Thank You

[mcavic]

Google has many different data centers, and each one can possibly use a different ranking algorithm. Your browser can be hitting a different data center every 5 minutes.

As for www.mysite.com and mysite.com, some people link to one, and some link to the other. Google recognizes them as duplicates, and only displays one at a time. But which one it displays is basically random.

What you can do is use a 301 response to redirect all mysite.com hits to the same page at www.mysite.com, or vice versa, then Google will figure out which one you prefer. See here [webmasterworld.com].