Hello there,Even i'm facing the same problem with my new Arduino UNO. Steps i did after buying UNO as follows,
1)Refered arduino blinking led program and dumped code successfully to UNO and led blinks from port 13.I selected UNO board type,baudrate of 9600,serial port COM7.
2)Next day,when i connect it to pc,its detected as COM7 at ports in device manager.Then i tried simple ''hello world'' program from this website.But when i upload code to UNO i got error message as ''avrdude: stk500_getsync(): not in sync: resp=0x00 error
3)Now my pc is not detecting the UNO and it shows ''unknown device'' in device manager.
4)if i uninstall the driver and try to reinstall the driver,pc shows ''device driver is already installed''.
If its a problem of hardware,how can we check it?? How to check ATMEGA328P-PU ic on UNO board works fine or not?
Guys i don't know how to proceed now.Can anybody help us ??
Thanks in advance