ok here we go, print this out...
Reboot your computer (to make sure windows didnt bug up on you) try to delete the folder...
If that doesnt work.
Reboot the computer, and press F8 repeditively when you first start up (before the windows screen) when you get a selection screen, select "Safe Mode"
while in safe mode try to delete the folder.
If that doesn't work restart again, pressing F8 and select "safe mode with command prompt"
you will see C:\
here you will type (with quotes)
DELTREE "C:\Program Files\DAP\History\Guest"
shutdown -r -t 05
press enter again
your computer should restart within 5 seconds.
if this doesnt work, you may have to use the programs listed above by the other posters.