explorer hangs intermittently at startup

Sometimes when I'm being logged in, either from a restart or just a logout/login thing, it seems explorer is hanging on something. When it happens, I notice that not all the icons appear in the tray, and the mouse cursor changes to the busy cursor when I hover over the task bar. In addition, nothing on the task bar responds, though I can pull up the task manager and see that nothing is using significant CPU time, and seems normal for idling. When I log off using the task manager, a popup appears stating that explorer.exe is not responding, and asks if I want to end now or wait. If I log back in, it will suddenly work fine again. Anybody seen something like this before?

This is a fairly new computer, I've tested all the hardware extensively, and the windows install went cleanly. I did a little forum browsing, didn't find anything on topic, but it seems that more than one user is posting that norton AV is causing a bunch of problems. That is my AV program too.

EDIT> On a hunch, I tried disabling the startup scan from norton, and that seems to be 100% effective so far in removing the problem. This leaves me with the question, what is the best competitor to NAV these days?