NIS 2010 v17.5 - Intermittent Startup Failure

Starting immediately after I received the NIS 2010 17.5 update (via Live Update), I've been experiencing the following: About 20% of the time, when I start my computer, NIS appears to fail to load.  There isn't a tray icon, and if I select NIS or Live Update from the Programs menu nothing happens.  The two normal ccSvcHst.exe processes appear in Task Mgr; however, when I attempt to log off or shut down, I have to manually kill a ccSvcHst.exe to continue.

The other 80% of the time NIS starts up normally.  I can't identify any differences between conditions when it starts up OK and doesn't.

This never occurred until the 17.5 update.  After experiencing it, I tried completely uninstalling NIS, running the Norton Removal Tool, then re-downloading (this time it installed 17.5 as the base version vs upgrading via Live Update) and installing fresh--didn't make any difference.

Windows XP SP3.

Thanks.