I appreciate that some people hear their PVR hard drives spinning and searching. I don't. It's where I sleep and I hear all kinds of things, the furnace, fridges, freezers, sump pump, etc, but not my PVR. As was mentioned, it could be a failing hard drive, or just a noisy one. You can go into Diagnostics and check the DVR HDD INFORMATION page to see if it shows any bad blocks.
Not sure on the troubleshooting option (under settings) would do much.
Better to go into the FULL box diagnostics.. There is a hard drive option in there i beleive, which may say if there is failures, etc.
Unless its changed.. i am assuming it still works on the Navigatr..
Hold down exit till you see one of the lights on the remote blink (setup i beleive?) then press the down arrow twice, then 2.