The horizontal lines are due to an incompatibility problem between older Mas apps and PC vinyl cutting software.

Cutting software tends to be based on either plotting wares (such as Auto CAD) or PC vector graphic apps (such as Corel Draw).

I haven't seen this problem for a while though, but to be honest I haven't used Freehand for a while either.

Try exporting as a different format. perhaps a later one or even as a AI file, most modern sign plugins should be able to accept the latest illustrator formats