Canon S400 Reference Manual page 211

Check 4
Is there sufficient free space on the hard disk?
An error may occur if there is not enough free space available on the hard
disk. Check the amount of free space on the hard disk. If there is little free
space available on the disk, delete any unneeded files.
Check 5
Is there a problem in the file you are trying to print?
If one of these errors occurs only when you try to print a particular file,
there may be a problem in the file or the application program. Rebuild the
file and try printing it again. If there is no problem with the new file, the old
file was probably faulty.
If the same error occurs with the new file, call for help.
Application error, General protection fault
Troubleshooting - An Error Message Appears 211