Doubt it is an issue with your softmod. Games simply will work or not in that situation, for the most part.
Keep in mind that disk playing offers the most ability of failure through the console's hardware, and it is always recommended to back them up to usb devices for preservation and playability.
Could be a laser issue or just small imperfections on the disk that combined with other variables cause an error.
Some folks have reported that laying the console flat down seems to get better results, some say a good cleaning of the laser has helped, and others switch to more reliable media to burn their backups on.