Having troubles with Windows 7/64bit USB driver and the Mega 2560.
I connect the Mega 2560 and navigate to arduino-0022\drivers\Arduino MEGA 2560.inf
Windows 7 loads the driver and it shows up as Arduino Mega 2560 (COM7) and reports Device Status: This device cannot start. (Code 10)
If I run arduino-0022.exe->tools->serial port, COM7 does not appear on the picklist. Tried rebooting everything, no luck.
I notice no Windows 7 definitions in this file, it looks like the driver is old?
Uninstall the driver and follow these directions. See if that helps. It worked for me.
I uninstalled and then went through the install process again... and no luck 
Driver details shows C:\windows\system32\DRIVERS\usbser.sys (Ver. 6.1) which is up to date.
I'm not sure what else I can try.
I uninstalled and reinstalled the USB driver with reboots to the PC and having Mega 2560 disconnected.
That got the driver to start and Win7/x64 to report "This device is working properly".
But in Arduino software, it reported "The COM port is already in use".
Found the problem is the USB hub in my LCD monitor, plugging Arduino right into the PC works now.
I have been chasing this same problem and the fix was quite unexpected. As it turns out, the multiple usb ports on the back plane of the motherboard share the USB controller in many cases.
This poses the problem for the arduino driver and the other usb devices (i.e. mouse, keyboard, printer, etc...) on this one controller, raises a conflict in Win7 and causes the code 10 error. Move your connection to a usb port that uses a different controller possibly the on on the front panel, and your problem should go away. I was trying to isolate a driver conflict but this seems to clear the problem.
Best regards,
Gilbert
Hi! I have Freeduino Mega 2560, Windows XP SP3 (32-bit). I can't install driver for my arduino board. I installed Arduino IDE 1.5.4. I wasn't lucky in trying to reinstall driver. Windows doesn't see any driver in chosen folder (Arduino\drivers). Creating new Key RunOnce in Regedit didn't solve the problem.
Although this is old, the last post is still unanswered..
Freeduino USB Mega 2560 uses different serial to usb driver chip. A FT232RL
Drivers are here http://www.ftdichip.com/Drivers/VCP.htm