Lightroom Problem

All of a sudden Lightroom has started loading all my photos with a custom preset. They were not imported with this preset, even photos that are months old have this problem. Every time I load a photo from the library, it finishes rendering it with a custom preset. I have to reselect "Default" to get it back to normal. I dont want to have to do this for every photo, since I have too many. Also I cannot simply reset the entire library to default as it will switch all the photos that I shot in B&W to color. Has anyone else had the problem, or knows of a way to fix it?