I've bought an arduino mega 2560 clone and some bits and bobs to go with it, when I upload a sketch i may have to click the upload button up to 20 times for it to work. The times it doesnt work I get this error.
"Arduino: 1.6.7 (Windows 7), Board: "Arduino/Genuino Mega or Mega 2560, ATmega2560 (Mega 2560)"
Sketch uses 1,518 bytes (0%) of program storage space. Maximum is 253,952 bytes.
Global variables use 9 bytes (0%) of dynamic memory, leaving 8,183 bytes for local variables. Maximum is 8,192 bytes.
avrdude: ser_open(): can't open device "\.\COM5": Access is denied.
avrdude: ser_drain(): read error: The handle is invalid."
Apart from this I find that when I do get a sketch to run it lags or stops during the process, for example in the blink sketch, the led will stay on or off for a few seconds and then resume. If I breadboard a circuit with a button, it will work but sometimes the led will get stuck and be nonresponsive to the button. Similar situation with servos. Would love some help if you know what could be happening.
Sincerely, Robert.