Installation error with the Framework 3.5

As the title says, when I try install the Net framework 3.5 I get "An installation error has occured" (My comp isn't in english, I translated it, so it's not exact). Currently I have Mozilla 4.0, maybe I could download the Framework 4.0 instead and try with it, but where can I download that? (No I havn't searched for it yet, really xD )

It doesn't work with Mozilla 4.0 atleast, I tried to start it before too. I use Windows XP, but when I tried to start it complained and said I should login as administrator, but I AM the administrator! At my comp then, I asume? or.. did they mean 'administrator' for something else? It came two popups about every 5 second saying the same thing, one that I should be admin and the other seemed to be this black window with white text (You know, right?) which's used for programming. I forgot what it's called.
Then the popups stopped with a last one which told me the whole thing just failed.

Sooo... To sum it up I think I should try another Framework version.
I really appreciate any answers since I want to play this server. ._.'

Solved it! (With some help from a freind currently playing the server ) Now when I start SoulMS, first the normal GMS popup, then hackshield popup and then patch popup. At the patch popup it says my version is outdated and that I need to download a new version. Okay, it seems I didn't solve it anyways ;_;

Net Framework 4.0 Download.

If that doesnt solve your problem, i'll actually go over your problem and help you solve it.