Windows Explorer "waits" all the time

Since downloading critical updates from windows update,
everytime computer boots up, as soon as I click on
explorer, the system just waits. Ctrl\Alt\Del will clear
the waiting, but as soon as I click on Explorer or even
Control Panel, then same thing happens.
Even when launching Internet Explorer, page loading is
halted unless I use Ctrl\Alt\Del to end task Explorer,
then the page will reload normally.
Any Ideas???

Thanks