Lunar Magic says that the author of the hack has restricted level access. What's this?

The ROM is "locked", which means that you can't open it in Lunar Magic.

Why would an author lock their hack?

To prevent others from accessing the levels and potentially stealing level data, Map16 data, custom graphics, and other resources.

Lunar Magic won't open. It gives me a message saying that it has been modified. How do I fix this?

Redownload Lunar Magic.

Lunar Magic opens the ROM, but it tells me that its checksum is bad. What's this?

If you just downloaded this ROM, then it's probably a bad dump. If you edited it with another program such as Asar or AddMusic before using Lunar Magic, it's probably fine. Make sure Maintain Checksum in the Options menu is checked.

I edited my hack in an older version of Lunar Magic, and everything became glitched! What happened?

This is a known problem with editing a hack made in Lunar Magic 1.7 and newer in Lunar Magic 1.63 and older. To avoid this, stick with one version of Lunar Magic.