The clip is appearing in MSC mode, but not MTP? Let your new device charge first in the MSC mode (the battery logo will “roll” until fully charged).
Then disconnect, and turn it on. On the device, select Settings > Info, and let us know the firmware version that pops up. The current build is 1.01.20. If you have the early 1.01.11 version, the Clip will be trying to connect in MTP mode.
Since this mode is our issue, we can try reconnecting first. If you have a USB Mode selection on the device, select "auto Detect and try again. Does the Clip say “connected”?
On the PC, go to “My Computer”, and look for the sansa, and see if it is listed under “Devices with removable storage” or “other”. If it’s in “Devices”, it’s recognized in MSC mode, and not MTP.
The problem will be in the Windows Media Player, as the MTP driver is part of that.
Let us know what you see!