Well, the songs showing up as “Unknown” could have something to do with the ID3 tags. You would go through WMP to edit those (library, right click on song, Advanced Tag Editor).
As far as the player allowing you to only utilize 100MB of space … If you connect your player to the computer, open My Computer, right click on the drive for your player and select properties, how much space is it registering as available and how much is used? If it’s showing less than 1.84GB available, it could mean that in moving the new songs onto the player a sector of the memory became corrupt or one of the files did. In that case I’d suggest running an error check and then reformatting - or possibly just reformatting. If you reformat, be sure the player is in MSC mode, connect it to the computer, open My Computer, right click on the drive and select format. In that window, be sure that the File System is set to FAT32 and that Quick Format is NOT checked (unless you’re on Vista, then check it).
After you format, I’d disconnect, let the player restart and then reconnect to your computer. At that point go into My Computer and verify that the full memory is showing when you display the properties. If it is, then I’d try reloading new songs (after checking the ID3 tags so you don’t get that ‘Unknown’ error) possibly using WMP this time if last time you used the drag-and-drop method. I’d also try transfering different songs this time - ones that you know are ‘clean’, so either ones purchased online or ripped from a CD you own (ones you download from other sources can be corrupt and do funky things to your player!)
Once you get the new songs loaded, check to see if they’re displaying normally. If so, try loading more songs, but keep track of which ones you load and when. That way, if you hit a bad batch of songs (again), you’ll know which ones are causing the problem on your player and you can get them out of your library completely.
Hopefully something in this will help you out - if not, let us know.