FTDI Problem? Unable to download sketch from PC but can download from a Mac

I have a very strange problem which I have been trying to get to the bottom of for several days now with zero luck, so I am hoping someone out there has seen it before and knows how to fix it.

I have several Arduino boards which have worked OK up to now but I recently purchased a couple of Nano V3.0 units. I first used them with my MacBook Pro and had no problem writing code and programming them via the USB cable.

I then went to program them at work using my Dell PC and got the old “avrdude: stk500_getsync(): not in sync: resp=0x00” message. A quick look on the internet threw up a host of similar problems and i investigated and checked every one of them but none were the cause of my problem.

I put a logic analyser on the serial lines and what I saw was that the RX pin on the ATMega328 was getting serial data at the correct baud rate but each character was in fact a null character. No mater what was sent to the serial port it was sending down a null.

I put a scope on just to check that there wasn’t a problem with the logic analyser and it showed the same thing.

So given that the Nano works fine when connected to the MacBook Pro, and that the IDE works fine with Arduino Mega328 and the Diecimila everything is pointing to a problem in the FTDI driver. But I have installed it on two different PC’s one with Windows 7 32-bit and one with Windows 7 64-bit and I have run both the latest driver and the previous version with the exact same failure so surely some other people must have seen this problem before me.

Any ideas what can be the cause of this? Here is a list of the hardware etc.

  1. Arduino Nano V3.0
  2. Arduino IDEs used 1.05, 1.52, 1.5.5-r2
  3. Hardware used MacBook Pro with Mavericks, Dell Latitude with Windows 7 64-bit, Dell Optiplex 780 with Windows 7 32-bit
  4. FTDI drivers used 2.8.28.0 and 2.8.30.0

I apologise for x-posting but I think my original post was in the wrong forum but it appears that you can’t delete your own messages.