dsoakley,
There is a published KnowledgeBase for this error in using LabVIEW 6.1. You can get to it
here.
You may also want to post what file had the error instead of having to look inside the failure log and give a better description of what you VI does and what it calls. I would also include what version of LabVIEW you are using. It is best to give more information than what you think is needed so that this forum can be the most helpful.
Randy Hoskin
Applications Engineer
National Instruments
http://www.ni.com/ask