Vista - WindowsUpdate_0000066A" error code

can any one help with this error code 000066a the update is for security net framework 1.1 got rid of first error code but I do not know how to correct this one please help?????????

some error codes are produced when the files that need to be updated are in use, I suggest trying to update while system is idle and all non essential processes are not running, failing this, I would uninstall the previous versions of .net framework and download the redistributable from here > Download details: .NET Framework 3.5

sorry im not sure if im on rigth place .
i have windows vista home premium 64bit .
ive my computer just for 40 or 50 days and the last time i could get update for it.
18/12/2008 now when i seach for updte its says win is up to date .
all computer seams to be ok the problem i had was when i instaled new version of messenger it stuck once .
then since it stuck i went to live one care and run a safety scan
only the registry scan and it stuck at 96% and never end .
just for you guys know ive used one care antivirus free trial i unistall it culd be the problem ?
hope someone helps thank you