Index: firmware/usbstack/usb_hid.c
===================================================================
--- firmware/usbstack/usb_hid.c	(revision 24309)
+++ firmware/usbstack/usb_hid.c	(working copy)
@@ -25,7 +25,7 @@
 #include "kernel.h"
 #include "usb_hid.h"
 #include "usb_class_driver.h"
-/*#define LOGF_ENABLE*/
+#define LOGF_ENABLE
 #include "logf.h"
 
 /* Documents avaiable here: http://www.usb.org/developers/devclass_docs/ */
@@ -180,6 +180,7 @@
 static int cur_buf_send;
 
 static bool active = false;
+static bool currently_sending = false;
 static int ep_in;
 static int usb_interface;
 
@@ -595,6 +596,7 @@
     logf("hid: init connection");
 
     active = true;
+    currently_sending = false;
 }
 
 /* called by usb_core_init() */
@@ -611,12 +613,14 @@
     cur_buf_send = 0;
 
     active = true;
+    currently_sending = false;
 }
 
 void usb_hid_disconnect(void)
 {
     logf("hid: disconnect");
     active = false;
+    currently_sending = false;
 }
 
 /* called by usb_core_transfer_complete() */
@@ -627,6 +631,7 @@
     (void)status;
     (void)length;
 
+    logf("HID: transfer complete: %d %d %d %d",ep,dir,status,length);
     switch (dir)
     {
         case USB_DIR_OUT:
@@ -638,6 +643,7 @@
 
             send_buffer_len[cur_buf_send] = 0;
             HID_BUF_INC(cur_buf_send);
+            currently_sending = false;
             usb_hid_try_send_drv();
             break;
         }
@@ -787,7 +793,15 @@
     if (!length)
         return;
 
+    if (currently_sending)
+    {
+        logf("HID: Already sending");
+        return;
+    }
+
+    logf("HID: Sending %d bytes",length);
     rc = usb_drv_send_nonblocking(ep_in, send_buffer[cur_buf_send], length);
+    currently_sending = true;
     if (rc)
     {
         send_buffer_len[cur_buf_send] = 0;