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As I never filled my 5045’s HD to the brim, I am not sure what happens once the disk is full. From what I imagine, your DVD recorder is either miscalculating the free space or if a recording is physically located at the end of the HD, it may assume it is full, even though there may be a lot of free space in-between the recordings.
There are a few options you can try. The first would be to perform disk defragmentation, which is an option that can be found on the tools menu. However, if you have not defragged the hard drive in a long time or since you got the player, I would recommend leaving the defragmentation process to run overnight as it can take several hours if the HD is fairly fragmented.
If defragging the hard drive does not help, try upgrading the firmware to the latest version (if you have not already done so), just in case it is a bug that may have been fixed in a later firmware version.
Unfortunately, if neither the above tips work, your only other option is to backup what you have on the HD and perform a full format. For recordings that are larger than the discâ€™s capacity, use the â€˜splitâ€™ tool to break the recordings down to chunks that can fit onto blank DVD media. At least you only have 10 recordings, so a small spindle of DVD+/-R’s should handle that.