You need the driver for it ..it should be on the cd that came with the mp3 player ..It is an older model and it work s with driver ..try to see if it has the driver on the root folder....If when you plug it in .. letter appear in the my computer ..even if it is not the removable drive you expect ..try to see what you have inside..and run the execution if you find a software inside..(Usually this will have a disk drive characteristic if it is like I say ..) Or ..just insert the disk if you still have it ..and run the driver ...than insert the mp3 player ..
If it is not seen at all ..not even as unknown device ..than it is damaged..or need to install the firmware on it ..Try though to change the usb port ..
I looked over the memorex but it do not hold support for these devices..either are too old..or in is under another name by make..so ..the only hope is the original cd ..

Rght click on "my computer" go to properties, click on hardware,click on device manager,with your mp3 plugged up. Look for the icon with the yellow box with an exclamation point which represents uninstalled software. Right click on it and click update driver and follow the directions.

If the above does not solve it, check for a small reset hole on the device. Using an unfolded paper clip, push the button to reset it. Then try to plug to the computer again.

Hi:
This may be because your USB input is 2.0 high speed usb bus, and the unit works with the old standard 1.0 usb bus. This may cause communication errors with the card and the computer, also the card itself could be defective, I suggest you check onling for a upgrade device driver for the player the will allow the unit to use USB 2.0