@Crax M587 should never be in a print file. I expect this is file corruption on the SD card. Either it has uploaded to the SD card with an error (less likely as you say you have printed it without problem already), or the SD card is corrupting the file. Older versions of the firmware had problems if you were running a print and uploaded a file at the same time. Current firmware versions have CRC-32 checksum checks for uploading files, so there shouldn't be any errors.
Update your firmware, upload a fresh version of the gcode file, and if the problem continues replace or reformat the SD card, and copy on fresh files (but backup your configuration files first!).
Ian
