Does Not Update (automatic Or Manual)

I am running Windows Vista Home Premium and connect to the internet via a wireless router (Sky). I installed MSE a couple of weeks ago, but upon checking yesterday I found that it actually does not update (automatic or manual), instead it gives me the error message "Virus & Spyware definitions update failed. MSE was not able to check for updates - make sure computer is connected to the interned and try again", even though I am clearly connected to the internet (actually using it whilst trying to update MSE).

Having read your forum I uninstalled MSE, used a clean up tool to remove any potential remainders of previous anti-spyware programs and re-installed MSE. Initially the virus update worked fine, scanned the laptop and thought problem sorted. This morning, out of interest, I tried to update the virus definitions again, just to see if it works, but no, I am now getting the same error message again...also, for quite some time now, when Windows informs me that there are updates available and I try to install these I get an error message, plus I can't log into Messenger either?