I know this is going to seem like a dumb question but…are you sure the headphone plug is all the way in? This has happened to a lot of people with new Fuzes–including me when I got one. It sounded exactly like the file was skipping.
Don’t be brutal, but push in the plug and twist it. The jack is tight, especially at first.
When a file starts jumping, look at the display. If the time is changing smoothly, that’s a sign that it’s playing but not getting through the headphone jack to you.
If it’s an old Fuze, the headphone jack may be giving way. But if it’s just eight months, you are still under the one-year Sandisk warranty and should call 1-866-SANDISK.
You might also try playing that file on your computer to make sure the file is not bad. You could even run a checksum on both files to make sure they are identical.
http://www.softpedia.com/get/Security/Security-Related/Little-MD5-Creator.shtml
Another thing you could try is reloading the firmware. See what hardware version your Fuze is (1.x or 2.x) in Settings/System Settings/Info. 2 is not an upgrade of 1–it’s for a different Fuze.
Download the All Regions zipfile of the correct firmware (1.x or 2.x) from the thread below. Despite what the thread says, DO NOT install the updater–there’s no need for it since there will not be any more updates.
http://forums.sandisk.com/t5/Sansa-Fuze/Sansa-Fuze-Firmware-Update-01-02-31-amp-02-03-33/td-p/139175
Unzip it on your desktop and drag the files you get onto the Fuze driveletter (like E: SANSA FUZE or whatever your computer says). Disconnect and it will redo the firmware.