Sounds like the WMDRM secure clock is the issue.
There are two ways to synchronize the clock using the Rhapsody 4 client. Well, there’s a third, but it isn’t as consistent.
First, the most basic: open the client and plug in your Sansa. Then be sure to log in. The client should read the license and track data and update automatically. If you click on the Sansa, the license date should show in the lower right corner.
Next, ignore that goofball “license” button. I think that it was simply designed to make the “licenses updated successfully” message pop up on the status bar only. Whether it updates the Sansa is subject to relative humidity, the barometer being above 997mb, and the solar wind being below 6.2 protons per cubic meter. So, deauthorize then authorize the Sansa by right clicking on the device in the sources pane of the Rhapsody client.
Lastly, I’ll show you the secret handshake, but remember, once I show you, the RealNetworks black helicopter may be sighted buzzing nearby. Hold the [control] + [shift] keys depressed, move your mouse over the Sansa, and right-click on it. Ah, yes, it’s a case of computer Twister for your clicking pleasure! Reset Secure Clock will be an available option.
Oh, as all roads lead to Rome, you can also force an update by dragging and dropping a single song track from the library or Music Guide, over to the Sansa. This will start the update process as well.