A few days ago i got a Leonardo becourse i wanted to use it for my new project.
But its now for pickup for free, or i wil trow it out of my car window.
Dispiet all the good advices on the forum and website i gant get it to work.
It wont accept a sketch be uploaded, it says i have com4:, but it tryes to use com3: for programming.
Reading the facts and trying to hold the reset until the upload message apears, nothing works.
This is a waisted $25
Throw it very very strong thru the window so it lands here 
This is the error message i get
System wide configuration file is "C:\arduino-1.0.3\hardware/tools/avr/etc/avrdude.conf"
Using Port : \.\COM4
Using Programmer : avr109
Overriding Baud Rate : 57600
AVR Part : ATmega32U4
Chip Erase delay : 9000 us
PAGEL : PD7
BS2 : PA0
RESET disposition : dedicated
RETRY pulse : SCK
serial program mode : yes
parallel program mode : yes
Timeout : 200
StabDelay : 100
CmdexeDelay : 25
SyncLoops : 32
ByteDelay : 0
PollIndex : 3
PollValue : 0x53
Memory Detail :
Block Poll Page Polled
Memory Type Mode Delay Size Indx Paged Size Size #Pages MinW MaxW ReadBack
eeprom 65 10 8 0 no 1024 8 0 9000 9000 0x00 0x00
Block Poll Page Polled
Memory Type Mode Delay Size Indx Paged Size Size #Pages MinW MaxW ReadBack
flash 65 6 128 0 yes 32768 128 256 4500 4500 0x00 0x00
Block Poll Page Polled
Memory Type Mode Delay Size Indx Paged Size Size #Pages MinW MaxW ReadBack
lfuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
Block Poll Page Polled
Memory Type Mode Delay Size Indx Paged Size Size #Pages MinW MaxW ReadBack
hfuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
Block Poll Page Polled
Memory Type Mode Delay Size Indx Paged Size Size #Pages MinW MaxW ReadBack
efuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
Block Poll Page Polled
Memory Type Mode Delay Size Indx Paged Size Size #Pages MinW MaxW ReadBack
lock 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
Block Poll Page Polled
Memory Type Mode Delay Size Indx Paged Size Size #Pages MinW MaxW ReadBack
calibration 0 0 0 0 no 1 0 0 0 0 0x00 0x00
Block Poll Page Polled
Memory Type Mode Delay Size Indx Paged Size Size #Pages MinW MaxW ReadBack
signature 0 0 0 0 no 3 0 0 0 0 0x00 0x00
Programmer Type : butterfly
Description : Atmel AppNote AVR109 Boot Loader
Connecting to programmer: .avrdude: Send: . [1b]
avrdude: Send: S [53]
avrdude: Recv: S [53]
avrdude: Recv:
avrdude: Send: V [56]
avrdude: Recv: V [56]
avrdude: Send: v [76]
avrdude: Recv: v [76]
avrdude: Recv:
avrdude: Send: p [70]
avrdude: Recv: p [70]
Found programmer: Id = "Sÿ("; type = p
Software Version = V.
Is there a way to get the orgional USB drivers and not the ones supplied with Leonardo?
Which IDE do you use?
Have you tried to install the new 1.0.4?