diff --git a/src/apps/activitymonitor/ActivityView.cpp b/src/apps/activitymonitor/ActivityView.cpp
index 73947ce6d1..689f79053f 100644
--- a/src/apps/activitymonitor/ActivityView.cpp
+++ b/src/apps/activitymonitor/ActivityView.cpp
@@ -225,6 +225,11 @@ void
 ViewHistory::Update(DataHistory* history, int32 width, int32 resolution,
 	bigtime_t toTime, bigtime_t step, bigtime_t refresh)
 {
+	if (width > 16384) {
+		// ignore this - it seems the view hasn't been layouted yet
+		return;
+	}
+
 	// Check if we need to invalidate the existing values
 	if ((int32)fValues.Size() != width
 		|| fResolution != resolution
diff --git a/src/apps/activitymonitor/CircularBuffer.h b/src/apps/activitymonitor/CircularBuffer.h
index 5063f7d349..12ff3ada55 100644
--- a/src/apps/activitymonitor/CircularBuffer.h
+++ b/src/apps/activitymonitor/CircularBuffer.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2008, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
+ * Copyright 2008-2009, Axel Dörfler, axeld@pinc-software.de.
  * Distributed under the terms of the MIT License.
  */
 #ifndef CIRCULAR_BUFFER_H
@@ -40,7 +40,12 @@ public:
 
 		fSize = size;
 		fBuffer = (Type*)malloc(fSize * sizeof(Type));
-		return fBuffer != NULL ? B_OK : B_NO_MEMORY;
+		if (fBuffer == NULL) {
+			fSize = 0;
+			return B_NO_MEMORY;
+		}
+
+		return B_OK;
 	}
 
 	void MakeEmpty()
@@ -61,7 +66,7 @@ public:
 
 	Type* ItemAt(int32 index) const
 	{
-		if (index >= (int32)fIn || index < 0)
+		if (index >= (int32)fIn || index < 0 || fBuffer == NULL)
 			return NULL;
 
 		return &fBuffer[(fFirst + index) % fSize];
@@ -75,7 +80,8 @@ public:
 		else
 			index = fFirst++;
 
-		fBuffer[index % fSize] = item;
+		if (fBuffer != NULL)
+			fBuffer[index % fSize] = item;
 	}
 
 	size_t Size() const