When you get a message that there is "no disk in the machine", it is a Windows error (not a RootsMagic error) that means your database has links to media items (like images) that are on a drive that doesn't exist anymore.

This could be links to media items which were on a CD, but there is no CD in the drive.  Or to a flash drive or external hard drive which isn't plugged in anymore.

You can try:

1. Putting a CD in the drive before trying to open RootsMagic.  Any CD is fine... you are mainly trying to keep Windows from accessing a drive with no disk in it.
2. Plugging a flash drive into your computer.  Again, you are trying to keep windows from accessing a drive that doesn't exist.

You can also try running the Multimedia Report (Reports > Lists > Multimedia list) to get a list of all the media your file links to.  You can look at that report to try to find which media links are pointing to the CD drive or another non-existant drive.