We were developing an Android multimedia application in the bad old 2.x days, and our QA person was running into a crash recording with the camera in our app.
She walked over to my desk to show me, and the crash wouldn't happen anymore. Went back to her desk and was able to reproduce it again, walked back to my desk and suddenly it wouldn't happen anymore.
After a bit of this, I finally brought my laptop over to her desk and discovered it was an out of memory error issue. She sat by the window, and with more sunlight at her desk she was getting higher frames per second from the camera, whereas in my dark corner the camera was recording way fewer frames and using less memory.