Use 'find' to locate files matching regular expression

I'm trying to write a `find` command to locate files/directories within a certain directory matching a certain regular expression. As it is written now, I'm running a simple find, piping over to `grep`, then piping over to `xargs` to move the file.

The problem arises when a directory matches the expression. Due to the way that `find` handles directories and their contents, the directory is listed first in the result, causing it to be moved, but then the `xargs`command tries to execute the `mv` command on the directory contents (because the pattern matches the parent directory which is part of the `find` output) which are no longer where they were before the command was issued, causing an error ("mv: cannot stat `/path/to/file': No such file or directory") to be generated. This command is part of a script that is called by cron, and these errors generate annoying emails to me. The end result is what I want, but there has to be a better way of writing this line to prevent these errors.

I want to incorporate the regex and the mv into the find command itself, using the -regex and -exec options, but I haven't figured out how to do it yet. The -regex is what is holding me up - probably something to do with the -regextype, but I'm lost there as well. Haven't been able to find anything documenting -regex and -regextype online.

This is running on RedHat Enterprise Linux 5 as part of a BASH script.

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# The command as it is run now
find /home/USER/files/received/ | grep -E "/[Cc]64-[0-9]{1,2}-[A-Za-z]{2,5}-[0-9]{1,2}|/[Cc]64-[0-9]{1,2}-[A-Za-z]{2,5}-[A-Za-z]-[0-9]{1,2}" | xargs -I "%" mv "%" /home/USER/files/sorted/
 
# I want to use something like this to prevent the "mv: cannot stat" errors
find /home/USER/files/received/ -regex "/[Cc]64-[0-9]{1,2}-[A-Za-z]{2,5}-[0-9]{1,2}|/[Cc]64-[0-9]{1,2}-[A-Za-z]{2,5}-[A-Za-z]-[0-9]{1,2}" -exec mv "{}" /home/USER/files/sorted/ \;