Visa Serial Communication via Serial port COM# is unreliable

Hi! Guys,
could you please help me with a recurrent issue?. I think it's very interesting . Well, I'll try to explain it clearly.
I work with a master's project, where I'm using a Arduino Mega Atmega 2560 and Labview to valide a GUI to working with a serial communication via VISA read and write funtions. Using a specific serial port COM. I have found several answers about this issue in the Web. But I do not have yet a clear solve of this. The reccurent issue is the follow: When I run my application do not problems with open sesion serial port, and reading/writing way is correct. but after a time, the communication is not stable because there are slow iterations in moments or iterations frozen, even there are interations with a communication broken finally. I have tried with enable events, termination caracters (line feed and carriage return), Bytes at serial port and etc...
I think all hardware by NI have a excellent performance with the transference of data using GUIs by Labview, but using different hardware is not. I attach the VI's used.