Weird reinstall message-about to throw computer out window!

I'M TRYING TO DO A CLEAN REINSTALL OF WINDOWS XP MEDIA EDITION ON MY  INSPIRON E1505. DURING SETUP IT PROMPTS ME TO ENTER THE SERVICE PACK PRO DISC 2, WHICH I NEVER NEEDED DURING PREVIOUS REINSTALLS. IT NEEDS AN "ASMS" FILE, IT SAYS. HOW TO FIX? I HAVE NO OTHER COMPUTER TO GET THIS FILE FROM, AND CAN'T GET INTO REGEDIT. I'M HOPING IT'S NOT AN OPTICALDRIVE ISSUE. THANKS-SORRY FOR ALL CAPS-CAN'T TURN IT OFF!