Hello Dave M, Thank you for contacting National Instruments.
Saving to and reading from large library files is very memory intensive. This is most likely leading to your error. Please refer to the LabVIEW User Manual (Chapter 7, pp. 12-13) at the following link: http://www.ni.com/pdf/manuals/320999e.pdf The following Knowledge Base is also useful: http://digital.ni.com/public.nsf/websearch/D5662AF762385C1A862566C2007FE40F?OpenDocument The recommended limit of VIs in a library is 255. This number can vary depending on you memory capacity. It is also recommended that your libraries not exceed 1 MB in size. To avoid this error, you might want to consider dividing your library into multiple libraries. Put your high-level VIs in one library and group other VIs by function. Alternatively, you can save your VIs in a Development Distribution directory by selecting File >> Save with Options... and selecting the Development Distribution option. Let me know if you need any more help. Sean C. Applications Engineer National Instruments