diff -p -up Mesa-7.8.1/src/mesa/drivers/dri/intel/intel_blit.c.orig Mesa-7.8.1/src/mesa/drivers/dri/intel/intel_blit.c
--- Mesa-7.8.1/src/mesa/drivers/dri/intel/intel_blit.c.orig	2010-05-07 15:48:44.000000000 -0300
+++ Mesa-7.8.1/src/mesa/drivers/dri/intel/intel_blit.c	2010-05-07 16:43:47.000000000 -0300
@@ -265,6 +265,9 @@ 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);
@@ -369,6 +372,7 @@ intelClearWithBlit(GLcontext *ctx, GLbit
       OUT_BATCH(clear_val);
       ADVANCE_BATCH();
 
+  clear_bit:
       if (buf == BUFFER_DEPTH || buf == BUFFER_STENCIL)
 	 mask &= ~(BUFFER_BIT_DEPTH | BUFFER_BIT_STENCIL);
       else