A. A. Explorer is just a process so you can stop the Explorer process and then start a new one. You should use caution with this though and you will also lose the service type icons on the taskbar when Explorer restarts.
- Right click on the task bar and select Task Manager
- Click the Processes tab, select explorer and click "End Process"
- Click the Applications tab and click "New Task"
- Enter a name of explorer and click OK
- Close Task Manager