Attempt to dodge some known vbo issues (VAO quriks, and VBO mapping being wonky). Will investigate the issues further, soon.

indra/newview/llviewercontrol.cpp

@@ -377,8 +377,12 @@ static bool handleAudioStreamMusicChanged(const LLSD& newvalue)
 
 static bool handleUseOcclusionChanged(const LLSD& newvalue)
 {
-	LLPipeline::sUseOcclusion = (newvalue.asBoolean() && gGLManager.mHasOcclusionQuery 
-		&& LLFeatureManager::getInstance()->isFeatureAvailable("UseOcclusion") && !gUseWireframe) ? 2 : 0;
+	LLPipeline::sUseOcclusion = 
+			(!gUseWireframe
+			&& LLGLSLShader::sNoFixedFunction
+			&& LLFeatureManager::getInstance()->isFeatureAvailable("UseOcclusion") 
+			&& newvalue.asBoolean() 
+			&& gGLManager.mHasOcclusionQuery) ? 2 : 0;
 	return true;
 }