I have been trying to see all the files in computer, but since accesses of some files are denied my program throws exception. When I show the type of exception with a MessageBox I learnt it is about mscorlib.dll. I can make my program run not throwing exception using assemblies. But if I wanted to prevent the program to throw exception what would you suggest to me to do? Should I download and set up, or I saw somebody had a similar problem and he solved it uploading related file, *.dll . By the way, I use C# for my application.