If you’re lucky it’s a firmware glitch rather than a worn-out wheel. Go to the firmware thread (near the top) and follow the manual installation instructions. Basically you download the file, unzip it, drag it over to the SANSA CLIP driveletter and let it load.
Don’t use the updater because it will think you already have the right version. (And if you have the updater in your computer, you might as well uninstall it–no more updates coming.)
If the firmware doesn’t fix it, it’s probably busted. Try eBay for an original Clip (they turn up now and then) or elsewhere on line for a more recent model. If you seriously only need low capacity for podcasts, you could also go back to Sansa’s C, E or M series, super cheap, though they probably have less battery life since they’re old.