Another one here I'm afraid. I had a Cateye Strada wireless computer for a couple of years. Excellent kit. Stoped at my local shop to get new batteries. Fitted them, re-mounted computer on the stem. Rode off. Heard a clatter going downhill at around 25 mph. Thought nothing of it. A mile later, looked down. No computer. Now I know what the clatter was.
Retraced my route, no sign of computer - must have bounced into the long grass and I decided that searching through all that over a about half a mile of verge on a busy road was going to end in tears, so gave up. £40 odd for the computer, plus £7 for 2 new batteries. Yup, make sure you've got it well clicked home before you ride off.
Bought another, and you can be sure that I now double check that it's clicked home. At least I now have mounts for 2 bikes, and a computer to swap between them. Only have to remember which is wheel size A, or B.....
Andy