CJMW 5 Newbie Poster

SO im writing a simple map editor using c# and xna. Ive just finished with xml serilization, but when i compile i get the following error: "Unable to generate a temporary class (result=1).
error CS0016: Could not write to output file 'c:\Users\Chris\AppData\Local\Temp\1vw3tjxm.dll' -- 'Access is denied. ", what does this mean? And how can I solve the problem?