There are several issues at play here: the internal versus external memory (microSDHC), a Mac, MSC mode, and a quirky error message.
I’ll try to shed a little light on the error message first, Not enough space for Music DB. Please free 200MB. This message simply refers to corrupted blocks of memory, and how the Sansa interprets it. There may be a number of files that are either truly corrupted, or the device cannot handle them, or the file allocation table can have errors. The amount of requested “space” in the message can range from one file (message will be 6MB or so) to the “200” you see here, if there are multiple issues.
It’s rare that the device is actually out of space, unless you’ve tried filling up the device completely with a media manager like Windows Media Player, using the “auto sync” feature. Note that, in this specific case, Windows Media Player will give you a “the device is full” error message before you even unplug the device, allowing you to correct the situation.
The most common issue I see with this message is a corruption in the File Allocation Table. This is a record, in all memory venues, be it a floppy disk, magnetic hard drive, or flash based memory, that tells the computer where everything is stored within that media. It’s a critical piece of information, and if there’s something wrong with it, things will go wonky indeed.
If you have errors in the removable microSD card, the Sansa will have a problem when trying to build the music database. Simply remove the card first, then see if the Sansa operates happily without the card. You can either try checking the card for errors using a card reader and your PC, or use the Sansa as the reader when it’s plugged in. This is a handy way to isolate the memory area with a possible corruption.
Let’s go back to the Sansa for a moment. If the device isn’t accessible in MSC mode, turn it off. You can try resetting the device, if it is frozen, by holding the power button depressed for 20 seconds or so. With the device off, you can manually force an MSC connection by holding the center “select” button depressed while plugging the USB cable in to your PC. This tells the device to connect in Mass Storage Class mode, as a flash drive.
You can now check the file allocation table by using the chkdsk utility from a DOS prompt (if you’re comfortable with old school), or go to Windows Explorer / My Computer and locate the Sansa. Right click on the listing and select properties , then the Tools tab, then select “Check Volume For Errors” to see if the FAT can be corrected.
If not, you’ll have to format the device by right clicking and selecting Format. This clears all data (media) from the device, so you can start anew, but you’ll have to reload your music over again. Select FAT as the format if your card or Sansa is 2GB or less, otherwise, select FAT32.
The Mac has a nasty habit of inserting a little table of its own, those wee ._ entries peppered all over the place. There are many forum posts regarding cleaning these up, search for “Mac” here on the forum and you’ll see.