first, simply try rebooting and see if you can then delete the file..

if that fails, then reboot again and start hitting F8 when the boot sequence starts..this will bring up a boot options menu..choose safe mode...this should then enable you to delete the file in question...one note, safe mode does NOT use your standard video drivers, which in a nutshell means your whole desktop is going to get hosed as far as where you have all your icons located...you will have to move them back as you like after you reboot again to get back into normal operating mode