Wellington, are you by any chance trying to update your development server working copy with your post-commit hook? I'd recommend svn update or svn update --force over checkout simply due to the fact that it only brings changed files, not the whole repository (save network bandwidth, time, etc.)
If the dev server wc is on the same server as your svn it should be as simple as cd /var/www/path/to/wc svn update . That said, I've never fiddled with hook scripts; only read about them. I'd love to see how you did this since I'd use it too... I just haven't gotten around to it.
