You'll probably have to give a lot more information in order for us to be able to give you much help with this one. One thing to look into is whether the program is using a hardware interface such as data acquisition. If it is you may need to install DAQ support for LV 7.0 or support for another hardware interface. If you haven't already run the driver CD after installin LV 7.0 it is a good idea to do so. You should also make sure your program handles errors properly (has all of it's VIs connected with error clusters and an error handler at the end), VIs without proper error handling are very tough to troubleshoot.
Regards, Ryan K.
