Help .net framework v4.0.30---- error

Error .net framework v4.0.30 - does anyone encounter this error in your computer? please help...i already had downloaded the net framework from microsoft and installed it but i still couldn't install autocad application, my 3dsmax is also affected with dialogue box notifying error everytime i open it....i am thinking of re-installing again my os but i would like to consult it first here for second opinion....thanks for your help...Godbless....