I have an application that I was able to build and run just fine, I have done something to corrupt my :\WINDOWS\assembly\GAC_32\mscorlib\220.127.116.11__b77a5c561934e089\mscorlib.dll, it does not find the assembly files and no symbols load now. I am not sure what I did or added to cause this. I tried running dotnetfx.exe and it gives me an error not compatible with the installed version error. Is there anything I can do other than re-installing VS and all my plugins? I am working at a large client and we do not have full administrative rirghts to our machines. How do these assemblies get coruptted and how do I avoid doing it again? Any help would be greatly appreciated.