A buffer overwrite error is usually caused by the scope generating data faster than the program fetches it. At a MS/s sample rate, you are acquiring 24MBytes of data per second, so you have a relatively large throughput. However, your analysis is fairly inefficient. In particular, you use the memory manager a lot to manage arrays. There are a couple of posts you should read which will help a lot. First, check out Managing Large Data Sets in LabVIEW. This info is also in the LabVIEW help files of newer versions of LabVIEW. Next, check out this more directed post which explains your immediate problem.
I would also suggest you check out how to make LabVIEW state machines and task handlers. Your code is getting fairly large and difficult to modify (although you are still keeping it relatively clean). A state machine architecture would solve this issue (with lots more subVIs). Look in the LabVIEW help first, then search these forums. If you have questions, let us know!
