Start + E shortcut freezes taskbar

I recently had a problem with a Windows Update going bad (for Internet Explorer I believe) that has resulted in the following behavior:

when the computer is rebooted and after Windows has to all appearances finished loading (system tray icons are all loaded, no hourglass cursor ...), if I use the Start button + E keyboard shortcut to try to open Windows Explorer, I freeze the task bar I can still move the mouse cursor but that's about it.  The taskbar will eventually unfreeze itself after a minute or so and then Windows Explorer will open.  Sometimes this will happen a second time, sometimes this will only happen once during the beginning of a computer session - after the 1st or 2nd time, the problem goes away (until I restart the computer) and the computer acts normally.  Another weird thing - if I open Windows Explorer using the shortcut in the Start Menu then I don't see this problem - only if I use the Start + E keyboard shortcut does this problem happen.

After trying several things including a System Restore and finally a Dell PC Restore to put the computer back to factory settings, I'm still having the problem.  Oh, and right after the bad Windows Update occurred and I saw this problem, I updated my anti-virus (Symantec) and my anti-spyware (Malwarebytes) and did full scans with both and didn't discover anything (except for an unnamed tracking cookie that Symantec keeps finding).

The last thing I've tried is to use msconfig to disable all of the items in the Startup tab of the System Configuration Tool (except the nvraidservice.exe process as I wasn't sure if my computer would be OK without that running).    That didn't help (I've since turned everything back on in msconfig).

I'm considering doing a complete reinstall (repartition -> reformat -> reinstall) but would like to see if anyone has any alternate ideas or suggestions.

Thanks!