OK, I'll take a guess ... is it Windows XP ?
If yes, then see this (ignore the title) and do Method 1 first:
Updates are not installed successfully from Windows Update, from
Microsoft Update, or by using Automatic Updates after you repair a
Windows XP installation
http://support.microsoft.com/kb/943144
MowGreen [MVP 2003-2008]
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*-343-* FDNY
Never Forgotten
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Nicholas Barham wrote:
> I am having some troubles with my laptop; where I can't install some updates.
> I can't install the latest Windows Media Player and I can't install Windows
> Live either. It will download the .exe for both but it will not install it.
> It keeps saying that it has failed to install. I don't understand why it is
> doing it. I have just re-installed my Operating System and this has
> happened. Can someone help please?
>
> Thanks