vista windows update - check for updates is disabled

I have recently upgraded to vists (business) from xpsp2 pro on Sony Vaio SZ
laptop.

2 issues -

a)I keep getting a pop-up "Restart your computer to finish installing
important updates", a small window in the right above the systray. I have
been restarting several times..... but it keeps nagging.

b) I went to the 'Windows Update' under control panel to manually
update/install. On the left-side menu, I notice 'check for updates' is
disabled. So, I can not even do the updates manually, right?

Please help me fix the (a) nagging window and (b) enable the 'check updates'
menu item.

Thanks.