You could try,.. run and type sfc /scannow (notice space between sfc and /
Or go to run and type in "sendto" (no speech marks) This will open your Send To
folder. Copy all the shortcuts there to another folder, ie: put them on your desktop, then delete the original options that are there. Replace each option back in the folder one at a time and right click and sendto that program.
You should find the one (hopefully only one) program that is causing the problem.