Exactly what does the error message say? I don't remember one that says that the file is too large and does not allow the user to continue. Where are you backing it up to? Are you using compression? I can see you getting that error if you are backing up to a CD (or some small drive like that) with no compression and the file being backed up is too big to fit on the target drive. If you use compression, the file will be split up.
WinRescue does have an error message that is given at the end of a backup and is given when backing up to a CD with no compression. It says:
Files were found that were too big to fit on a CD. These files were skipped. Consider compressing the backup if you want to back up these files.