mp3 file transfer

hello everybody. i have a 1gb mp3 player. i can copy and paste music onto it no problem. the problem is that when it gets about halfway full, i am told via a windows error message 'cannot copy (enter song name here) : parameter is incorrect'. i have no idea what i should do to solve this. i have checked the removable media properties which tells me that there is still half of the space empty. how do i fill this space?
thanks

ps. it came with a disc that has a format option but i didnt want to just go ahead and format it in case it formats the programs used to play the music. this would be most upsetting.

Most mp3 players won't let you copy moer than a certain number of files to the root level of the player, 127 I think.

Create a folder in thr root level and then copy the songs into that folder.