Troubleshoot on a Virtual Machine (if you absolutely must run old files).

is an older, legacy masking plugin originally from Corel (formerly from Ultimatte) designed to help remove backgrounds. The specific version number you mentioned ("v10387") does not correspond to a known official release from Corel or any major software archive. It strongly resembles a version string sometimes attached to modified, cracked, or pirated software circulating on unsafe download sites.

This is the "killer feature" that made KnockOut 2 famous. Standard masking tools often leave a "halo"—an ugly rim of background color around the edge of your subject.