Hey guys, I'm using several Arduino nano 3.0 boards since more than a year.
I didn't encounter any problems on my Win8 64bit or Win7 64bit machine ever, so I didn't hesitate to update the drivers when the windows update told me there are newer drivers available.
Of course I didn't check everything after updating the driver, as working with Arduino isn't my daily business...
Now I noticed that there is no communication available with my self-build millingmachine running GRBL on a Nano.
So I connected another 'fresh' Arduino to check if I'm still able to upload sketches using the Arduino IDE. But that's the point.
I'm not able to conenct to my arduinos anymore.
I've been searching for days to find a solution, have been installing the newest FTDI drivers, connected the Nano to different ports. Unsuccesfully 
Now I don't have any further idea what to do.
The IDE keeps telling me that avr dude was lost in synchronisation:
-Uflash:w:C:\Users\Cysign\AppData\Local\Temp\build8081340622992327180.tmp\Blink.cpp.hex:i
avrdude: Version 5.11, compiled on Sep 2 2011 at 19:38:36
Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
Copyright (c) 2007-2009 Joerg Wunsch
System wide configuration file is "D:\Programme_consistent\arduino-1.0.5\hardware/tools/avr/etc/avrdude.conf"
Using Port : \\.\COM5
Using Programmer : arduino
Overriding Baud Rate : 57600
avrdude: Send: 0 [30] [20]
avrdude: Send: 0 [30] [20]
avrdude: Send: 0 [30] [20]
avrdude: Recv:
avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude done. Thank you.
Uploading sketches to my Uno (without FTDI chip) still works.
As I'm still able to use the Nona with my Windows 8 64bit system I'm sure the Nano isn't broken.