Need some help RE Adware/Spyware...

I wonder if someone would be kind enough to guide me in the right direction.  I am not too understanding of major high tech computer jargon so the advice will need to be in simple english :smileyhappy:

 

This morning an annoying Windows popup kept coming up in the bottom right hand area of the screen off a red circle with a white X through it saying that my computer is infected with spyware and to click here to download a programme to remove this spyware, but when you clicked on the yellow pop up box, nothing happens.  Also, my desktop picture has been removed and i have been left with the plain blue screen, and when going into Desktop properties to try and get a picture back, I find that these items are "frozen", you cannot click on a picture to use as desktop.

 

So I re-started the computer in Safemode and ran a full systems check with Norton Antivirus 2006.  It came up with these two problems which it said were of a low risk, they were "Adware.Spysherriff and Adware.Savenow".  I got Norton to "remove" these adwares and then restarted the computer in normal mode.  The annoying windows pop up with the red X circle has now gone from the bottom right panel, but I still can't get my desktop back to normal, it stays on blue and will not let you click on any desktop pictures in properties to set it to.

I hope this makes sense and I have not made myself or you more confused.  Some help would be greatly appreciated. 

Thank you.

Michelle