diff -urN openglide_org/grguBuffer.cpp openglide/grguBuffer.cpp
--- openglide_org/grguBuffer.cpp	2009-02-15 23:53:23.000000000 +0100
+++ openglide/grguBuffer.cpp	2010-10-26 14:22:27.000000000 +0200
@@ -98,6 +98,13 @@
     OGLRender.FrameTriangles = 0;
 #endif
 
+    // Carmageddon never unlocks the buffer before calling BufferSwap
+    if ( Glide.DstBuffer.Lock )
+    {
+        grLfbUnlock ( Glide.DstBuffer.Type, Glide.DstBuffer.Buffer );
+        Glide.DstBuffer.Lock = true;    // Re-lock the buffer
+    }
+
     SwapBuffers( );
 
 #ifdef OGL_DEBUG