Black bar appears on bottom of the image with film camera?

I recently received a Minolta XD11. I took a roll of film and decided to test it out for the first time. After developing the film, i see that about 5 shots in the roll have a black bar appearing on the bottom of the image and covers up about 1/4 of the picture. Another 2 shots came out completely black. I notice this only appeared during the day shots and under bright lighting conditions. All of the shots taken in the night or under lower light came out fine. I did not use a flash with the camera so flash sync speed should not be the issue. I don't remember exactly the shutter speed and aperture values used in those shots but I do believe they were 1/1000 of a sec, which is where my camera tops off. I'm wondering if maybe the black bar is being caused by too fast of a shutter speed..? I've even tested the shutter with no film loaded and the back open, and it seems to be working fine without any lag or hiccup. Any ideas on what could be the problem? I'm stumped