Hello,
As
smercurio_fc mentioned, there are some known issues about using both the NI-VISA and the Agilent IO Libraries 14.1 on the same machines. You can look at this article for more information about this issue.
If you are not using the Agilent libraries, can you please give more information about the software and hardware you are using.
Regards,
O. Proulx
National Instruments
www.ni.com/support