I have an Uno R3 with CH340G which works perfectly at my home w7 x64 notebook.
It worked properly right away with the CH341s64.sys driver. I tried revs from 2009, 2011 and 2014 and it is working with either one.
On my w7 x64 desktop though the drivers somehow do not communicate properly.
If I plug in the device, windows recognized it and a new port (port 8 in my case) shows up in device manager.
When I try to transfer a sketch to the device it fails with error message
avrdude: stk500_recv(): programmer is not responding.
I have tried CH341s64.sys rev 3.3.2011.11 and 3.4.2014.8 without success.
I have no clue how I can troubleshoot this as windows shows the port properly and there are no signs of error on the driver. There are no entries in the event logs.
Is there possibly a log file from the IDE which could shine a light?
I already tried with firewall disabled but no change.
My IDE is the latest 1.6.6 on both systems.