Error Reporting for file commands

We've created a file manager which allows users to access their web space on a server. It's working brilliantly, except that it would seem there are some caching issues, either by the system cache or the web server cache that are causing us a headache. When the script tries to delete a file, we always check (using file_exists) to see whether the file exists before it's deleted. The check comes back true, but the unlink then fails, saying no file or directory there! We've tried turning off all errors (using error_reoprting(0) ) but this would seem to have little difference in the error - it still comes back with a failure. We are using our own error handling, but before the command is carried out, there is this 0 call... Does anyone know how we can stop these errors? Cheers Nunners