Slew limits are designed to stop your scope from either hitting itself, an attached accessory like a camera or pointing below the horizon.
Since an Alt-Az mount usually operates with the base horizontal, the lower slew limit is usually 0 degrees. However, on a wedge, the plane of the base of the mount now coincides with the celestial equator. So any slew command to an object like the Orion Nebula will result in the slew warning.
You can either simply press ENTER to bypass the error or you can set new slew limits. The new lower slew limit for a wedge-mounted scope should be your latitude in degrees minus 90.