diff -p -up Mesa-7.9/src/mesa/drivers/dri/intel/intel_blit.c.orig Mesa-7.9/src/mesa/drivers/dri/intel/intel_blit.c
--- Mesa-7.9/src/mesa/drivers/dri/intel/intel_blit.c.orig	2010-11-19 21:03:23.789708063 -0200
+++ Mesa-7.9/src/mesa/drivers/dri/intel/intel_blit.c	2010-11-19 21:03:50.177707924 -0200
@@ -263,6 +263,9 @@ intelClearWithBlit(GLcontext *ctx, GLbit
 
       /* OK, clear this renderbuffer */
       irb = intel_get_renderbuffer(fb, buf);
+      if (irb->region == NULL)
+	  goto clear_bit;
+
       write_buffer = intel_region_buffer(intel, irb->region,
 					 all ? INTEL_WRITE_FULL :
 					 INTEL_WRITE_PART);
@@ -370,6 +373,7 @@ intelClearWithBlit(GLcontext *ctx, GLbit
       if (intel->always_flush_cache)
 	 intel_batchbuffer_emit_mi_flush(intel->batch);
 
+  clear_bit:
       if (buf == BUFFER_DEPTH || buf == BUFFER_STENCIL)
 	 mask &= ~(BUFFER_BIT_DEPTH | BUFFER_BIT_STENCIL);
       else