When I attempt to reboot I can get no further than clicking my name. The next screen displays a window saying windows explorer has an error. Clicking that window leaves an empty screen with nothing but Dell wallpaper

What's the error?

Meanwhile, try booting into Safe Mode by pressing F8 while you're booting the system.

Once booted into safe mode, do a System Restore back a couple of weeks:
Click on Start > All Programs > Accessories > System Tools > System Restore
Click on Restore my computer to an earlier time and click Next
Select a date from the calendar a week or two back
Click Next and let the system do its thing...this may take a while.