'Unknown Publisher' problem

[Guest]

Just built a new computer and installed Windows XP SP2 with NIS 2007. I've
tried to update Norton, which has been successful as well as the Windows
Updater.

However, I've been trying to download and install programs like MSN
Messenger, but the computer says "there is too little disk memory or the
cabinet files are corrupt". I know I've not ran out of disk space (its 320gb
HDD...) and the Cabinet files aren't corrupt either. A full scan with
CCleaner and NIS tells me there are no problems.

Also, while trying to download drivers or patches to fix glithes on games,
the downloads are not digitally signed and won't install.

Is there any way to stop this?

 

[DL]

What is shown for properties of C: drive (My Computer)?
After installing winxp you installed chipset & other hw drivers from manu.
sites & NOT winupdate?

 

[Guest]

All hw drivers were installed from CDs supplied with the hw, the windows
updates had to be downloaded from the winupdate and NIS 2007 was updated via
the LiveUpdate function.

 

[DL]

And what size is shown for C?

All hw drivers were installed from CDs supplied with the hw, the windows
updates had to be downloaded from the winupdate and NIS 2007 was updated
via
the LiveUpdate function.