Desktop is corrupt - checkdisk will not run

This morning I logged in my NEW Windows Vista Dell Laptop 1525 (bought in May of 2008)

  and it says my Desktop is corrupt

so it says to run checkdisk - and I tried and checkdisk will not run

It starts to run - and stops when it says it has reached a large file

Another thing I attempted - I tried to run checkdisk and have it fix files,

  but it says that it can not run checkdisk because disk is in use,

and please schedule it to run on start up

so I did - but when I restart or shut down and start back up

Check disk does not run

 

Any suggestions?

As I said this computer is NEW

I have files on it transferred from my old computer - but not very many

I did not download anything new yesterday

I put it to "Sleep" yesterday and shut the lid

 

And Please - if you have suggestions

Keep them simple - I don't know what some computer terms mean

 

thanks very much