i got a problem i have hair modifier(grass) in cycles render. I can see it in material view and in solid view but when i press render grass(hair) desappears.
What blender version ?
Are you using gpu rendering ?
In blender 2.68 try using gpu and the feature set at Experimental
In Layers settings have you enabled ‘Use hair’
Have you read the manual http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/Hair_Rendering
Attach or post a link to your blend file
it worked when i changed to experimental.