Running Win 7 64-bit SP1 with 8 GB RAM. I first noticed this problem when using the GUI to copy some large (5+ GB) files from one disk to another. What happens is the physical memory in use rises quite quickly to 100% and the system comes to a crawl. If I just start to access the file in a media player (it is a movie) the memory usage climbs up slowly but eventually reaches 100%. When copying the same files via XCOPY I do not have this problem. Using RAMMAP I see most of the memory usage is under "Mapped File" and is allocated under the "Active" column. If I select "Empty System Working Set" the RAM usage drops back down but then starts to climb back up. Any ideas on what I can check/test to eliminate this issue?