Try removing the offending directory (gcc/testsuite/gcc.dg/special) and run svn cleanup again, updating the tree afterwards. If you didn't have any local changes in that directory you should not lose anything. If the problem persists then you probably have a hardware problem.
Just "for the record": gcc.gnu.org runs RHEL4, and we've never had any trouble like this. All the snapshots are generated locally using svn, etc.
