What do you mean when you say that the drivers 'appear' to work? Do they work in some cases, but not with other code that you have added? Also, did you try running the example program that Meghan suggested, and were you able to communicate with the instrument that way?
You say you have IVI and MAX installed. Do you also have 488.2 and NI-VISA drivers installed? What versions of all of these drivers do you have?
I mean that when I run the example programs for the instrument, there is no error. When I run my program, I get the memory error.
have NI-VISA and 488.2 installed. As for versions of IVI and MAX, I am
not sure how to find which versions, I just know that I am able to
communicate effectively with a Keithley instrument, so this leads me to
believe that the drivers that are installed do work. I think the MAX is
version 3.X, though I am not sure. I am using LabView7.0, and the
program suggested by Meghan does not work because it requires LabView
Not having 7.1 is no excuse for not running some basic GPIB commands. You have a shipping example for GPIB communication and you have the interactive control in MAX for doing GPIB communication.
The fact that you can communicate to a Keithley does not mean anything unless you are using an IVI driver for that. All of the software versions are listed in MAX. Just expand the 'Software' listing that you see there.
Lastly, if the examples work, narrow down which function call is generating the error. If it's the same one as mentioned in the original post and only that one, the simplest thing might be to perform the GPIB Write/Read without using the driver.