I'm getting exactly the same results under HP-UX with 5.6.1, down to the RE debug output.     This is perl, v5.6.1 built for PA-RISC2.0Removing the /s fixes the problem as you noted.

However, 5.005_02 under HP-UX doesn't exhibit the same problem:     This is perl, version 5.005_02 built for PA-RISC1.1Both versions were built from source tarballs, to my knowledge. If you'd like more info /msg me; I'm at a client site right now, but can respond as long as I'm here.

HTH