Sorted.
Just needed to download a free utility called windows installer cleanup from
http://majorgeeks.com/Windows_Installer_CleanUp_Utility_d4459.html
click on the bit where it says download sites, choose a site & it downloads automatically.
Then find it in start-- all programs, run it, then tick anything to with windows live (I also included silverlight)
you have to do each individual program separately I think.
Anyway I did that & when I opened messenger was able to download the update & bobs your uncle.
RESULT!!!
