Solutions to errors » Windows install error: downloads, but wont install?

this has been happening for about a week or so now, i try to install an update or program, like silverlight, and it doesn’t work. i download it fine, but the install keeps getting screwed up. the unpacking and stuff goes fine, then after i hit install, a window for windows installer pops up saying “the feature you are trying to use is on a network resource that is unavailable” which is unlikely since im like the only one on m network and it was downloaded to my hard drive. it says Click ok to try again but it always does the same thing, then it says try an alternate path, and gives a few options, none work, so i use the browse button to find the file and make the path, i find it, select it, it then takes a minute or two saying accessing feature, and then says the same thing again. when i hit cancel (the only way to get out of it) it just says install failed and closes. for the zune 4.0 it gives me an error and then tries to have me send in a error report, to which it opens another cant find feature window, and i have to close all of them leaving me annoyed and frustrated. any one got any ideas as to what this could be? ihaven’tt knowingly downloaded anything recently, and i installed norton 360 2010 last night and scanned everything without result besides a tracking cookie. any help on this would be great since this is really quite debilitating, thanks for the help
btw im running windows xp with all but the last two updates as they wont install…