[installation randomly closes?]

I have, but every time I try to download it, it tells me that the "setup has encountered an error and needs to close" then it rolls back and closes

[installation randomly closes?]

When I download the newest version of the program it'll start to install the .Net 3.5 Client Profile and get too about 10% and then stop installing and close.Every time I try to open this it does the same thing.I don't get any error messages it just stops installing, rollsback, & closes.Any help, please?