avrdude: ser_recv(): programmer is not responding.....please help

Hello everybody,
Before all, I beg your pardon for my poor english, I’m an Spanish speaker.
I’m not able to fix this problem uploading sketches to my arduino uno. The first day I had received it, it worked perfectly.
I’m working with an iMac OS X 10.7.5. and IDE 1.0.3. I was modifying and uploading without problem and then just the day after when I tried to go on again…the problem started.
I’ve read hundreds of post in this forum and googleing, but none of them have given me the solution.
The same board works perfectly all times on another PC (Pentium 4, Win XP) and laptop (AMD, Win Vista)…
One day surprisingly in one of my attempts trying to make it work, the arduino board works and accepted the sketch.
I don’t know why it worked, and in that moment I checked the technical enviroment and nothing have changed from before…Even it worked in a Win XP pro Virtual machine running under parallels in the iMac…But this didn’t lasted so long…
After some uploads the message started up again until now on my iMac but on PC’s works fine.
So I think that I have some things clear and a lot not so clear:
-My arduino board is ok, and has not problem because it works fine on another machines every time.
-Plugged on my iMac and running the loop test, the result of it is correct. So as the forum’s recommendations says USB, cable, FTDI usb-RS232 converter and board is ok. The Rx-Tx leds blinks correctly too.

I attach the verbose response of AVRDUDE working wrong on iMac.
Reading the response, it seems that IDE is talking with Atmel (Bootloader) without problem because ask information from Arduino and send to it commands to configurate it without problems, but just in the moment to upload de Hex file with the code, Arduino frozen and stop to talk with IDE…I don’t know why…

I appreciate very much your help.

Thank you very much in advance.

Luis.

avrdude: Version 5.11, compiled on Sep  2 2011 at 18:52:52
         Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
         Copyright (c) 2007-2009 Joerg Wunsch

         System wide configuration file is "/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/etc/avrdude.conf"
         User configuration file is "/Users/myself/.avrduderc"
      [color=blue]   User configuration file does not exist or is not a regular file, skipping[/color][b][color=red]<---Could be this the problem???????[/color][/b]

         Using Port                    : /dev/cu.usbmodemfd131
         Using Programmer              : arduino
         Overriding Baud Rate          : 115200
avrdude: Send: 0 [30]   [20] 
avrdude: Send: 0 [30]   [20] 
avrdude: Send: 0 [30]   [20] 
avrdude: Recv: . [14] 
avrdude: Recv: . [10] 
         AVR Part                      : ATMEGA328P
         Chip Erase delay              : 9000 us
         PAGEL                         : PD7
         BS2                           : PC2
         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                 :

blah-blah....

avrdude: AVR device initialized and ready to accept instructions

Reading | avrdude: Send: u [75]   [20] 
avrdude: Recv: . [14] . [1e] . [95] . [0f] . [10] 
################################################## | 100% 0.00s

blah....blah...

avrdude: reading input file "/var/folders/4m/8qq8bzw56sl7r0m1g492qc3h0000gn/T/build5901878382664752600.tmp/AnalogReadSerial.cpp.hex"
avrdude: writing flash (2596 bytes):

Writing | avrdude: Send: U [55] . [00] . [00]   [20] 
avrdude: Recv: . [14] 
avrdude: Recv: . [10] 
avrdude: Send: d [64] . [00] . [80] F [46] . [0c] . [94] 5 [35] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] y [79] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] x [78] . [01] . [0c] . [94] . [c6] . [01] . [0c] . [94] ] [5d] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] ] [5d] . [00] . [0c] . [94] ] [5d] . [00] 2 [32] . [03] . [11] $ [24] . [1f] . [be] . [cf] . [ef] . [d8] . [e0] . [de] . [bf] . [cd] . [bf] . [11] . [e0] . [a0] . [e0] . [b1] . [e0] . [e2] . [e1] . [fa] . [e0]   [20] 
avrdude: Recv: . [14] 
avrdude: Recv: . [10] 
##avrdude: Send: U [55] @ [40] . [00]   [20] 
avrdude: Recv: . [14] 
avrdude: Recv: . [10] 
avrdude: Send: d [64] . [00] . [80] F [46] . [02] . [c0] . [05] . [90] . [0d] . [92] . [a2] 1 [31] . [b1] . [07] . [d9] . [f7] . [11] . [e0] . [a2] . [e1] . [b1] . [e0] . [01] . [c0] . [1d] . [92] . [a5] < [3c] . [b1] . [07] . [e1] . [f7] . [10] . [e0] . [ca] . [e6] . [d0] . [e0] . [04] . [c0] " [22] . [97] . [fe] . [01] . [0e] . [94] . [03] . [05] . [c8] 6 [36] . [d1] . [07] . [c9] . [f7] . [0e] . [94] . [88] . [03] . [0c] . [94] . [07] . [05] . [0c] . [94] . [00] . [00] . [8e] . [e0] . [0e] . [94] U [55] . [01] . [bc] . [01] . [83] . [ea] . [91] . [e0] J [4a] . [e0] P [50] . [e0] . [0e] . [94] . [a1] . [04] a [61] . [e0] p [70] . [e0] . [80] . [e0] . [90] . [e0] . [0e] . [94] . [c1] . [00] . [08] . [95] . [83] . [ea] . [91] . [e0] @ [40] . [e8] U [55] . [e2] ` [60] . [e0] p [70] . [e0] . [0e] . [94] . [01] . [02] . [08] . [95] . [1f] . [92] . [0f] . [92] . [0f] . [b6] . [0f] . [92] . [11] $ [24] / [2f] . [93] ? [3f] . [93]   [20] 
avrdude: ser_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding