Hi,
Used to get an identical problem when I had my first experimental set it up in October last year. I have skylights across my whole classroom on one side and windows on the other. Sunlight or reflection can trigger this problem. Also if the batteries were a little flat, the frustrating problem you mentioned would happen. I have converted my wiimote to AC power and have never had the issue since, even with the skylights. It's been running 6 hours a day, 5 days a week - no problems. Check your batteries.