Not enough space for music DB. Please free 90MB

Just to be clear,most players require no special drivers.
Try this tip posted here on this site. You will see there are two sides to your player. One cant see the other.

Hello,

When the player is rearranging playlists of the music database, it is possible that there's not enough memory left in the player to finish the task.
Connect the player with your computer to delete some files, at least 90 MB, off the Fuze to make it work again.
When not having a backup of the songs, save them onto the computer first.

Here's the support site for Sandisk Sansa Fuze:
http://kb.sandisk.com/app/answers/detail/a_id/3249/session/L3NpZC93dDhKSlRaag%3D%3D/sno/0
Directly to the Sansa Fuze user manual:
http://mp3support.sandisk.com/sansa/UserManual/FUZE/fuze_userguide_en.pdf

Need more help ? Just add a comment.

There needs to be some space for the part that finds and tracks the songs. There are too many songs/pictures/video on your Sansa. Remove some. Its always good to have some extra space. Don't fill it up completely. Always leave 100megs free when loading the player.

Im Having the same problem with my sandisk player 8gb. It keeps saying , Free 90 mb and then powers off. HELP !!!!!!!!!!!!!!!!!

Remove the microSD card, then connect the Sansa to your computer. Delete one or more files (music, photos, videos) until you free up the required amount of memory.

It thinks you have tried to put a files on the MP3, called,  Music DB, and wants you to "Free Up" ie: delete unwanted files up to 90MB, old songs movies etc so it can complete it's job. However it may just be a fault?

you need to free space so it can use the firmware

See if you can back up your Fuze on your PC (if you haven't already done so) so you don't lose your music.
When your Fuze gives you the "90mb free space" error, you need to do a format of your Fuze as the database that tracks all the music on the Fuze has become corrupt and the Fuze can no longer refresh the database. You will have to format and erase and reload all of your data (music, movies) back onto the Fuze once this is done.
See if doing a reset will power your Fuze on if you still can't get it to turn on. To reset, slide the Power Switch up and hold it for approximately 10 seconds.
(Again this will erase everything, so make sure you have back it up first).
Next, Format the Fuze using the internal function (Settings -> System Settings -> Format -> Yes) and reload your music.

That player is not compatible with iTunes - sorry. Loading them onto there has corrupted your DB - go to Sansa'a website and download the Sansa Recovery Tool

What has happened is that when you connected the device to the computer if automatically downloaded everything on your media files thus filling up your MP3 player
You need to go in and delete the files you do not want. click the bottom part of the disk or dial and it will show a menu to delete FIRST,
you must let the battery run down(disconnect the cable and when the battery has discharged, you can plug it back in to recharge, then you can work with it to delete some of those files that are overloading you device This happened to me and this was the only way to unlock it when it locked up