diff --git a/cpu/avr/dev/usb/usb_descriptors.c b/cpu/avr/dev/usb/usb_descriptors.c
index 78d6c6b66..f934440b7 100644
--- a/cpu/avr/dev/usb/usb_descriptors.c
+++ b/cpu/avr/dev/usb/usb_descriptors.c
@@ -146,7 +146,6 @@ caps /* bmCapabilities */
 masterInterface, /* bMasterInterface, The controlling interface for the union (bInterfaceNumber of a Communication or Data Class interface in this configuration) */ \
 slaveInterface /* bSlaveInterface0, The controlled interace in the union (bInterfaceNumber of an interface in this configuration) */ \
 
-
 #define RNDIS_INTERFACES	\
 USB_INTERFACEDESC(	\
 	INTERFACE0_NB,	\
@@ -177,8 +176,6 @@ USB_INTERFACEDESC(	\
 	USB_ENDPOINT(ENDPOINT_NB_2,EP_ATTRIBUTES_2,EP_SIZE_2,EP_INTERVAL_2), \
 	USB_ENDPOINT(ENDPOINT_NB_3,EP_ATTRIBUTES_3,EP_SIZE_3,EP_INTERVAL_3)
 
-
-
 #define CDC_SERIAL_INTERFACES \
 USB_INTERFACEDESC(	\
 	INTERFACE2_NB,	\
@@ -208,10 +205,6 @@ USB_INTERFACEDESC(	\
 USB_ENDPOINT(ENDPOINT_NB_5,EP_ATTRIBUTES_5,EP_SIZE_5,EP_INTERVAL_5),	\
 USB_ENDPOINT(ENDPOINT_NB_6,EP_ATTRIBUTES_6,EP_SIZE_6,EP_INTERVAL_6)
 
-
-
-
-
 #define CDC_EEM_INTERFACES	\
 USB_INTERFACEDESC(	\
 	EEM_INTERFACE0_NB,	\
@@ -295,26 +288,43 @@ USB_INTERFACEDESC(	\
 //This doesn't seem to hurt anything but beware, system corruption is
 //a possibility.
 #if USB_CONF_MACINTOSH
+/* Prefer CDC-ECM network enumeration (Macintosh, linux) */
 FLASH uint8_t usb_dev_config_order[] = {
-	USB_CONFIG_ECM_DEBUG,    //Prefer CDC-ECM network enumeration
+	USB_CONFIG_RNDIS, //windows gets networking only (if not here gets serial only)
+#if USB_CONF_SERIAL
+	USB_CONFIG_ECM_DEBUG, //mac, linux get networking and serial port
+#endif
 	USB_CONFIG_ECM,
+#if USB_CONF_SERIAL
 	USB_CONFIG_RNDIS_DEBUG,
-	USB_CONFIG_RNDIS,
+#endif
+//	USB_CONFIG_RNDIS,
 	USB_CONFIG_EEM,
 #if USB_CONF_STORAGE
 	USB_CONFIG_MS,
 #endif
 };
 #else
+/* Prefer RNDIS network enumeration (Windows, linux) */
 FLASH uint8_t usb_dev_config_order[] = {
-	USB_CONFIG_RNDIS_DEBUG,  //Prefer RNDIS network enumeration
+
+//	USB_CONFIG_ECM, //windows doesnt like this here, will not go on to RNDIS
+#if USB_CONF_SERIAL
+	USB_CONFIG_RNDIS_DEBUG,
+#else
 	USB_CONFIG_RNDIS,
+#endif
+#if 0 //XP may have a problem with these extra configurations
+	USB_CONFIG_RNDIS,
+#if USB_CONF_SERIAL
 	USB_CONFIG_ECM_DEBUG,
+#endif
 	USB_CONFIG_ECM,
 	USB_CONFIG_EEM,
 #if USB_CONF_STORAGE
 	USB_CONFIG_MS,
 #endif
+#endif
 };
 #endif /* USB_CONF_MACINTOSH */
 
@@ -334,7 +344,8 @@ FLASH S_usb_device_descriptor usb_dev_desc_composite =
 , USB_STRING_MAN
 , USB_STRING_PRODUCT
 , USB_STRING_SERIAL
-, (sizeof(usb_dev_config_order)/sizeof(*usb_dev_config_order))
+, sizeof(usb_dev_config_order)
+//, (sizeof(usb_dev_config_order)/sizeof(*usb_dev_config_order)) //TODO:was this right?
 };
 
 
@@ -573,8 +584,9 @@ FLASH S_usb_language_id usb_user_language_id = {
 
 PGM_VOID_P Usb_get_dev_desc_pointer(void)
 {
+#if 1
 	return &(usb_dev_desc_composite.bLength);
-/*
+#else  //these are all the same length
 	if (usb_mode == rndis_only)
 		return &(usb_dev_desc_network.bLength);
 
@@ -585,15 +597,15 @@ PGM_VOID_P Usb_get_dev_desc_pointer(void)
 		return &(usb_dev_desc_eem.bLength);
 
 	return &(usb_dev_desc_mass.bLength);
-*/
+#endif
 }
 
 
 U8 Usb_get_dev_desc_length(void)
 {
+#if 1 
 	return sizeof(usb_dev_desc_composite);
-/*
-
+#else  //these are all the same size
 	if (usb_mode == rndis_only)
 		return sizeof(usb_dev_desc_network);
 
@@ -604,7 +616,7 @@ U8 Usb_get_dev_desc_length(void)
 		return sizeof(usb_dev_desc_eem);
 
 	return sizeof(usb_dev_desc_mass);
-*/
+#endif
 }
 
 
diff --git a/cpu/avr/dev/usb/usb_descriptors.h b/cpu/avr/dev/usb/usb_descriptors.h
index 328644649..f5648ebf7 100644
--- a/cpu/avr/dev/usb/usb_descriptors.h
+++ b/cpu/avr/dev/usb/usb_descriptors.h
@@ -65,11 +65,12 @@
 
                   // USB Device descriptor
 #define USB_SPECIFICATION     0x0200
-#if 1
+#if USB_CONF_MACINTOSH
 #define COMPOSITE_DEVICE_CLASS       0x02      // Misc
 #define COMPOSITE_DEVICE_SUB_CLASS   0x00      // Common
 #define COMPOSITE_DEVICE_PROTOCOL    0x00      // IAD
-#else //Windows wants these for composite device, but above seems to work anyway
+#else //Windows wants these for composite device
+//Above seems to work for Vista and Win7 but XP and Ubuntu 904 might need the old values
 #define COMPOSITE_DEVICE_CLASS       0xEF      // Misc
 #define COMPOSITE_DEVICE_SUB_CLASS   0x02      // Common
 #define COMPOSITE_DEVICE_PROTOCOL    0x01      // IAD
@@ -89,8 +90,17 @@
 
 #define EP_CONTROL_LENGTH     64
 #define VENDOR_ID             0x03EB // Atmel vendor ID = 03EBh
+
+#if USB_CONF_MACINTOSH
+//A different product ID avoids instant windows corruption when it tries to use the cached drivers
+//TODO:Get some valid ID's from Atmel
+#define COMPOSITE_PRODUCT_ID  0x9921 //Product ID for composite device
+#define NETWORK_PRODUCT_ID    0x9919 //Product ID for just CDC-ECM device
+#else
 #define COMPOSITE_PRODUCT_ID  0x2021 //Product ID for composite device
 #define NETWORK_PRODUCT_ID    0x2019 //Product ID for just RNDIS device
+#endif
+
 #define MASS_PRODUCT_ID       0x202F //Product ID for mass storage
 #define RELEASE_NUMBER        0x1000
 
@@ -229,7 +239,6 @@ enum {
 #define EP_SIZE_6           0x20
 #define EP_INTERVAL_6       0x01
 
-
 /*** Mass Storage ***/
 
 #define MS_INTERFACE_NB        0
@@ -280,7 +289,6 @@ enum {
 #define EEM_EP_SIZE_2           0x40  //64 byte max size
 #define EEM_EP_INTERVAL_2       0x01
 
-
 /******* ECM Configuration *******/
 
 // Interface 0 descriptor
diff --git a/platform/avr-ravenusb/contiki-conf.h b/platform/avr-ravenusb/contiki-conf.h
index e4dc8ca4f..7150208a8 100644
--- a/platform/avr-ravenusb/contiki-conf.h
+++ b/platform/avr-ravenusb/contiki-conf.h
@@ -184,16 +184,17 @@ extern void mac_log_802_15_4_rx(const uint8_t* buffer, size_t total_len);
 /* ************************************************************************** */
 /* Set USB_CONF_MACINTOSH to prefer CDC-ECM+DEBUG enumeration for Mac/Linux 
  * Leave undefined to prefer RNDIS+DEBUG enumeration for Windows/Linux
- * TODO:Serial port will enumerate in all cases and prevent falling through to
+ * TODO:Serial port would enumerate in all cases and prevent falling through to
  * the supported network interface if USB_CONF_MACINTOSH is used with Windows
- * or vice versa. If Windows has previously cached the RNDIS driver for the stick
- * it will attempt to use it and give "device can not start" error.
- * This doesn't seem to hurt anything but can potentially damage the OS!
+ * or vice versa. The Mac configuration is set up to still enumerate as RNDIS-ONLY
+ * on Windows (without the serial port). 
+ * At present the Windows configuration will not enumerate on the Mac at all,
+ * since it wants a custom descriptor for USB composite devices.
  */ 
 #define USB_CONF_MACINTOSH 0
 
 /* Set USB_CONF_SERIAL to enable the USB serial port that allows control of the
- * run-time configuration (COMx on Windows, ttyACMx on Linux, tty.usbx on Mac)
+ * run-time configuration (COMx on Windows, ttyACMx on Linux, tty.usbmodemx on Mac)
  * Debug printfs will go to this port unless USB_CONF_RS232 is set.
  */
 #define USB_CONF_SERIAL          1
@@ -201,8 +202,9 @@ extern void mac_log_802_15_4_rx(const uint8_t* buffer, size_t total_len);
 /* RS232 debugs have less effect on network timing and are less likely
  * to be dropped due to buffer overflow. Only tx is implemented at present.
  * The tx pad is the middle one behind the jackdaw leds.
+ * RS232 output will work with or without enabling the USB serial port
  */
-#define USB_CONF_RS232           1
+#define USB_CONF_RS232           0
 
 /* Disable mass storage enumeration for more program space */
 //#define USB_CONF_STORAGE         1   /* TODO: Mass storage is currently broken */