F--error even though I cleaned connections with lens and camera

Battery good?
Memory card in?
Was the camera dropped recently?
Lens connection may need cleaning, though you normally get error messages if the camera can't talk to the lens.

This seriously does work. I just took the battery out, placed it back in and when it was accessing I banged it (not even that hard) against my knee and it now can focus in and out. I almost can't believe that it worked, but it surely did.

Does this only happen with this lens? If other lenses work OK, then the problem is in the lens. If it happens with all lenses then it is in the body.

Try cleaning the contacts on the back of the lens and in the body mirror box with a Q-tip lightly saturated with alcohol.

How old is your lens? It may have a conflict with the newer camera body. Did it work right before?

Error 99 is Canon's depository for electrical connection problems and a host of other electrical orientated issues. Take a new pencil eraser and gently clean the contacts on the lens (gold) more a polish then a scrub and also do the same with the electric connections on the camera body again more a polish then a scrub. Make sure that no eraser dust has entered the camera body and if so clean it out by using a puffer with the camera lens mount facing downward, that way the partials will fall out not in. Also while you have the eraser handy clean both the contacts on your battery and inside the battery compartment. Another thing is to download your pictures from the memory card onto your computer and format the memory card in the camera. If all that fails then go to the Canon web site and download the updates to your camera's firmware.

What I full expect though is that the camera body to lens connections have become dirty and just need a little attention.

Hope this works for you

Then lens assembly could be stuck, or the battery could be low or weak. Make sure, first, that the contacts inside the battery are clean (clean them with a qtip and isopropyl alcohol). There's a couple of web sites that explain what things you can try to get it working, and they say about half the cameras can be made to work trying their suggestions:
http://camerarepair.blogspot.com/2007/12/fixing-lens-error-on-digital-camera.html
Even though the title of this page is lens errors, it applies to "stuck lens", and has steps to take to try to fix it.
This site is for battery problems, which is the other thing that might be going on with your camera:
http://camerarepair.blogspot.com/2007/11/simple-fix-for-dead-cameras-that-wont.html
Try these things, and you have a good chance of getting the camera working again.

I have the same problem with the same camera, and this is the help one of these Experts gave me. Didn't work for me but give it a try. Good luck.

The lens assembly could be stuck, or the battery could be low or weak. Make sure, first, that the contacts inside the battery are clean (clean them with a qtip and isopropyl alcohol). There's a couple of web sites that explain what things you can try to get it working, and they say about half the cameras can be made to work trying their suggestions:
http://camerarepair.blogspot.com/2007/12/fixing-lens-error-on-digital-camera.html
Even though the title of this page is lens errors, it applies to "stuck lens", and has steps to take to try to fix it.
This site is for battery problems, which is the other thing that might be going on with your camera:
http://camerarepair.blogspot.com/2007/11/simple-fix-for-dead-cameras-that-wont.html
Try these things, and you have a good chance of getting the camera working again.

Make sure your battery is fully charged, clean the contacts on the batteries and inside the camera
If that doesn't work, try the suggestions on this site:
http://camerarepair.blogspot.com/2007/11/simple-fix-for-dead-cameras-that-wont.html.
If none of those suggestions work, it could be a jammed lens. Try these steps:
http://camerarepair.blogspot.com/2007/12/fixing-lens-error-on-digital-camera.html
Even though the web page is titled "lens errors", it applies to stuck lens, also.
Good luck, hope this helps, and please rate this answer if it helped you.

Two possibilities: one bad, one not so bad. If you've recently dropped the camera you've likely damaged the lens tube (housing), and the camera will require professional repair. Before you panic though, the problem that you described is frequently battery related. Make sure that your batteries are the correct type for the camera, and that they are fresh/fully charged. If the batteries are OK, the problem may be due to corrosion on the contacts inside the camera. Remove the batteries and wipe the inside contacts firmly with a dry cloth (heavy corrosion may require cleaning with a wire brush, steel wool, or sand paper). Remove any residue that may have fallen into the battery compartment during cleaning, wipe the ends of the batteries, and replace them in the camera. This cleaning process works about 90% of the time, and I hope that it cures your problem.

try cleaning the lens contacts of your lens and camera.

This error... lens error.. can be the result of many abuses. If the lens is held back as it is extending, it can damage the tiny parts. If the lens is bumped while it is extended, it may damage the internal parts beyond repair. Sometimes the lens get off track as a result of a blow while extended.
If the camera is dropped, the lens mechanism can be damaged from the impact, even though it is not extended.
If you treat a digital camera with a lot of care, and put in a padded camera bag, you may extend the life of the camera.