There is a known problem with the Adafruit bootloader and driver (early versions and modifications at least) causing bluescreens.  The early Adafruit stuff was based on a now-obsolete Leonardo bootloader.  Best bet is to do like sth77 suggests and burn the Leonardo bootloader from Arduino 1.0.1 or later.

Confirming what Clamon and others have said, there does seem to be an issue with Leonardo drivers on a few specific models of Dell and, apparently, HP laptops.  I'm working with one community member now to track down the bug and hope to have a fix soon.

Clamon, I know it has been some time but did you ever find a solution for this?  I've heard a few other people having this problem on Win7 and am trying to get it solved.  Any information you can provide would be very helpful:
* Win7 architecture (32- or 64-bit)
* make and model of your computer
* are there any hubs between the computer and the Leonardo?

I think he meant having the Leonardo "type" directly into fields in Excel.  Something like this (assumes you start with a fresh Excel sheet in cell A1):

Code:

void setup()  {
  delay(5000);
 
  Keyboard.print("A1 text");
  Keyboard.write(KEY_TAB); 
  Keyboard.print("B1 text");
  Keyboard.write(KEY_DOWN_ARROW);
  Keyboard.print("B2 text");
  Keyboard.write(KEY_RETURN);
}

void loop() {

}

funkyguy, what version of Win7 are you running?  Also, can you please open Device Manager and send the Hardware IDs reported for the Leonardo?

What happened when you followed the driver install instructions?  Did it work at all?

This should be possible but you'll need to recompile the Uno's "optiboot" bootloader for the ATMEGA32U4 (you can change the target in the Makefile). 

clamon and alfoe,

Please try this:
0. connect the Leonardo directly to the computer's USB port (not through a hub).  also, disable any virtualization or security software that may intercept USB traffic.
1. open Device Manager and scroll down to the Leonardo icon
2. press reset on the board
3. as soon as the Leonardo icon reappears, double-click to open its dialog
4. this should be the settings dialog for the bootloader not the sketch (the two modes look different to the OS).  confirm by checking that the VID/PID is 0x2341/0x0036 (not 0x8036)
5. try installing the driver for the bootloader by pointing Windows to the drivers/ folder

While you're doing this you'll see the bootloader disconnect and the sketch connect in its place.  That's alright - as long as you leave the bootloader dialog open everything should work fine. 

Once you finish installing the bootloader driver you'll need to install again for the sketch.  It should succeed this time.

mkwired, sorry - had overlooked your message.  I can't take much credit - most of the implementation was done by a brilliant guy named Peter Barrett. 

Almost everything I know about USB has come from working with Dean Camera's LUFA project (http://fourwalledcubicle.com/LUFA.php), reading Jan Axelson's USB Complete book, and reading the specs until my eyes bled.

Can you provide the VID and PID numbers for the board as given by Device Manager?

The "iProduct" string sent by the board on enumeration tells the operating system gives the human-readable name.  The value of that string is set near the top of USBCore.cpp in hardware/arduino/cores/arduino/.  It's a Unicode string so you're looking for 'L', 'e', 'o', 'n' [...] not "Leonardo".  The string used depends on the PID number of the device (also sent during enumeration) which is given in boards.txt.

Just be aware that if you'll be distributing your own custom hardware based on the Leonardo that you'll need to provide your own VID.

Thanks for this.  From your results, the bootloader is definitely starting (see the "Found programmer: Id = "CATERIN"; type = S" line) but times out before the upload (see a little later when it gets a write error then reports "Found programmer: Id = "pÿ""; type = ç").  I'm surprised that it takes the Leonardo so long (at least six seconds) to reenumerate after reset - that's much longer than typical. 

How frequently do you get this upload problem on the T410 versus how often does upload work?  Are you running any virtual machine or security software on the T410 that could be interfering with or slowing down the enumeration of new USB devices? 

ScottG, how soon after the reset are you opening the Serial Monitor?  If you open the monitor while the bootloader is running it will happily connect but then be orphaned when the bootloader ends and the sketch starts.  Unfortunately there is no indication that this has happened, you just end up with a monitor window that is attached to a port that doesn't exist anymore.

josto, can you send the status messages after a failed upload attempt (turn on verbose output in preferences first)?  I'd have to see more to be sure, but your timing problem theory may be correct.  Some hubs (and, by extension, the root hub in each computer) introduce their own delay when a USB device is trying to enumerate. 

If nothing else, you should be able to manually reset the Leonardo and get a successful upload every time. 

That 1 ms polling rate is true only for HID (the keyboard and mouse) which use the USB interrupt transfer type.  CDC (which Leonardo refers to as Serial) uses the USB bulk transfer type which doesn't guarantee timing but does guarantee that it will transfer the data as fast as possible.  That "fast as possible" depends on what else is happening on the bus AND on the host computer.

In practice this does lead to different maximum transfer speeds for Serial on different computers (and even on the same computer under different workloads).  I don't have a board with me right now but, from memory, you can usually assume at least several tens of kb per second, up to a few hundreds of kbps.

It's not necessary to call Serial.begin() for the Leonardo since the CDC device is initialized elsewhere.  The stub was retained for backwards-compatibility. 

Serial (which talks CDC over USB to the host) and Serial1 (which talks to pins 0 and 1 via the UART) are both definitely available and usable on the Leonardo.

Pylon is right.  The Leonardo only works as a USB device - to support a USB joystick/foot pedal/controller you need a USB host.  This USB host shield may do what you want: http://www.sparkfun.com/products/9947 

I know the XBox controllers use a protocol similar to USB but is it 100% compatible?