Error 99 can most times be remedied by taking a standard pencil eraser and carefully cleaning the gold contacts at the back of the lens and the gold maching contacts in the lens opening of the camera... BE CAREFUL not to let eraser crumbs into your camera... keep it clean... reset the battery and give it a whirl.... did it solve the 99 issue?
for the CF it refers to the cf card... here's what I've found on this:
Canon reports that this error code may appear on your digital camera’s LCD (liquid-crystal display) when there is an error reading from or writing to the inserted CF (CompactFlash) card. This error code occurs most often after a user has tried to eject a CF card before the camera has finished writing data to the card.Solution:
Canon suggests that you first try to use a different CF card. If you do not see the error message when you use the new CF card, the first card is probably damaged.

Before you take the next step, drag the files from the CF card to a location on your hard drive to back up the files. Next, you can use Windows’ ScanDisk utility to check the CF card for errors. If you use a Mac, you can use Disk Utility (in Applications\Utilities\) in OS X.

If ScanDisk or Disk Utility fails to resolve the CF card problem, insert the CF card in your camera again. Then format the CF card. On most Canon cameras, you can do this by pressing the Menu button, selecting the Format tab, highlighting Format, selecting Format, and choosing Yes. Make sure you have backed up the data on the card before you do this. Formatting the card will delete the images from the card. After you format the card in your camera, use ScanDisk or Disk Utility to check the CF card again. If you still encounter errors while using ScanDisk or Disk Utility, you should discard the CF card because it is damaged.

If the error still occurs after following the steps above, your camera may need repair. Contact Canon’s technical support for further assistance.

hope this solves your issues....
let me know
K