Hi,

At the risk of muddying the waters further -- I have seen an error where the serial monitor is erratic -- will hang after running for a few seconds. 

Sometimes closing and reopening the com port can get it working again, other times not. Some times the port will open and no data will come over at all. 

I would also see this com problem if I tried the serial monitor in the Arduino ide. 

I managed to get past this by going to the device manager and removing all "phantom" com ports and usb devices. 
(go to device manager and select View>Show hidden devices)

It seems that Windows will periodically reassign my device to a different com port between sessions or compiles. This leaves the old port I was using still in the device list as a phantom. When the device I am working with goes from com 3/4 to 6/7 I will generally start seeing lagging problems and eventually serial monitor will not work at all. 

If I go through the device list (in device manager) and uninstall all the phantoms and then do a reboot I am able to use the serial monitor again. 

It looks like something I will have to do periodically. 

Thanks,

I'm a bit of a compulsive up-grader so I generally have the latest code.