I had three ROMs up until about an hour ago, and they were all capable of saving to the one emulated VMU nullDC had. I then downloaded another ROM, MDK2, but when I started it up it said, "A VMU with at least 12 blocks free is required for saving. Press the A button to continue." I'm not sure if I installed nullDC properly (I used a YouTube walkthrough video), because I downloaded it and then I also had to move vmsbrowser.exe into the nullDC folder from Chankast. I've been messing around with both vmsbrowser.exe and nullDC (with backups of course, in case I screw up), but I can't seem to add a second VMU. If anyone knows a way I can do this, I'd appreciate it greatly. Thank you.