**System Information**
Windows 7 64bits Nvidia GTX 580
**Blender Version**
Blender 2.75
Worked: (optional)
**Short description of error**
Derived mesh result of a bezier curve object with a Smooth modifier applied differs between the 3D viewport and Blender cycles rendered version
{F231697}
**Exact steps for others to reproduce the error**
Check attached file {F231696} or
[Shift + A] and Add > Curve > Bezier
Toggle into edit mode and [A] select all
[Shift+D] duplicate the default segment a few times around
Add an Smooth modifier to the curve object
Set it's extrusion to non zero
Compare viewport openGL object and cycles rendered results
This is probably a minor and known issue, and seems somewhat related to rB87211a49ab1c, reported according to Sergey's advice