Hi guy,
I installed backup files for Drupal 6 running over Windows server. Drupal is installed in a subdir http://host.com/drupal/
I can't get it work due to realpath failure. The path seems to be ok for a linux environment.
I add this workaround. It try to get the realpath in windows way if the linux way failed.
May it be usefull ?

## version: backup_files-6.x-1.1
## file: backup_files.module
## line: 157

$rp = realpath('.'. $bp. trim($dir));

// START PATCH
if (!$rp){
$dir = substr($dir,0,1)=="/" ? $dir : "/".$dir;
$rp = realpath(substr( ereg_replace("\\\\", "/",($cwd.$dir) ), 2));
}
// END PATCH

if ($rp) {
$relpath = substr($rp, $lcwd);
backup_files_scan($rp, $lcwd, $files);
} else {
drupal_set_message('Does not exist: '. $dir, 'warning');
}