Use Windows Performance Monitor. Select "Process" in the Performance Object control. Then select "Page File Bytes" in the Counters List control. Then select "LabVIEW" (or the name of your LabVIEW executable) in the Instances List control. Add this to the graph and watch it over time while your vi is running. If graph trends up, you have a memory leak.
If you do have a memory leak, look for instances where you open a reference without closing it over and over (queues, vi ref's, notifiers, etc.).
Tim