VI Run Sporadically Freezes Entire Computer

[Gashington]

Hi,

I am having a critical issue with a VI I wrote and I'm not sure why. The VI writes to a GPIB address to control an Agilent DCA, then reads data, then alters a parameter and repeats. It seems that the computer will randomly freeze while the code is running. An emergency restart, holding down the power button, is required to use the computer afterwards. It doesn't seem to matter how many loop iterations that code has gone through before it freezes, I have seen it freeze after just two and I have seen it freeze after 100. The only thing I can think of is that somehow the gpib write and read are causing some critical failure.

Is there something else on the computer that could be interfering/interacting with the VI that causes a system wide shut down? I've had the task manager open and CPU usage and memory never go above 25%. The two factors that have been constant for these freeze ups are that the vi is running and I haven't provided any user input to the computer (such as a moving the mouse) in a couple of minutes.

Thanks

[JÞB]

Lets see if my 8-Ball is calibrated today.

You are using a USB-GPIB converter.  And you have not used the windows device manager to disable the power management options on the USB hub.  So when the OS sees no user activity it shuts down the usb power and your whole system goes out to lunch.

[Gashington]

I don't believe I am using a gpib-usb converter but I'll check that anyways. I'll reply back if it freezes again. Thanks!

[altenbach]

How often is it at 25% CPU? Most likely you have a 4 core processor and highly serialized code, so you are actually running one core at 100%.

 The mentioned USB power issue is a good place to start. Do you use any other third party DLLs or drivers?

[Gashington]

I disabled the option in the USB root hub power management window that allowed them to turn off to save power and its been running for over an hour (I went to get lunch during this time so there was no user input) and its still going. I think youre right about the cores, one of the 4 windows showing cpu activities oscillates between top and bottom levels pretty consistently, I believe its correlated with reading and writing commands at the DCA on the GPIB port. I'm going to let it keep running, eventually this will need to be able to run for hours unnattended. I'll post back if the freezing issue reappears.