Virus

I have a HP Laptop with Windows 7 (64-bit) installed with Norton Internet Security 2011 came with the computer.  Since Sunday, (2) virus have showed up.  I have run a full scan with Norton & used the Norton Power Eraser.  This product erases the files temporarily, but when I re-boot it is back again.

I have upgraded to Norton Internet Security 2012 & still have the same virus showing up.  The virus are:  Donwloader.Dromedan and W32.Cridex.  Cannot find anything in the registry, but I am not one that modifies the registry unless I know what I am doing.  The files involved are:  25.11.pdf.exe and report.18653pdf.exe

 

Can someone tell me how to eliminate these (2)  virus & help remove the items in the registry?  Your help will be appreciated.

 

Thanks,

 

DarL