I had been modifying a circuit and program on my Arduino MEGA 2560 for several hours before testing it in lab today and everything worked fine until we started in the lab. The problem I am experiencing is that when any Arduino is connected to my laptop, it is only available to upload a program on rare occasions. The Arduino turns on and the L and On lights come on, but the TX does not flash like it does when it is attached to other computers. Essentially, there is a serial communication problem between only my laptop and various Arduinos, so my laptop must be the source of the problem.
I have tried reinstalling Arduino and checking to see if the Arduino is recognized as such in the devices list, which it is. Does anyone know what I did to cause this or how I can fix the problem?