Something is causing this problem. I actually found what was causing it, and I posted a solution for it it a couple of pages back. I'll repeat it here:
I found a solution to my problem that may be applicable to yours. In my case, the taskbar would freeze after a scheduled Mozyhome backup (but not after a manual backup). I fixed the problem by going to the system tray, selecting
Show hidden icons, hitting Customize, and changing the property for Mozyhome in the pull-down menu from "Show icon and notifications" to "Hide icon and notifications." The backup still runs and pops up a window as before, but it doesn't freeze the taskbar.
I suspect there is something running in your system tray that is causing your problem, and it might be fixable by changing the notification option. There are a number of ways you might attack this. One would be to change them one
at a time till the problem stops. Another way would be to change them all and see if that fixes it; then restore them one at a time till the problem reoccurs. If you have a lot of services running in the system tray, you might consider changing half of them
and using a bisection method to zero in on the service that's causing the problem. However, I wouldn't rule out the possibility that this is due to more than one service.
Good luck! :o)
I'm running Win7, but I would not be surprised if the same problem occurs with other versions. I would expect the same solution to work.