The display on my Ixus 500 has gone blank. It started to show weird colours when switched on but turning it off then on returned the display to normal. I knocked the camera the other day and the display is now blank both in camera mode and picture review mode. The camera makes the usual noises when selecting Menu etc. It also save picture to the memory card. Is it worth taking it to bits to look for a loose connection?

This sounds like it might be a defective CCD imager, and is a known defect for your particular model camera.. If so, Canon should fix this for you for free if you live in the US, Canada, and a select few other countries. If you live outside the US, contact Canon support for your country to see if they'll still honor the advisory (some still will, especially if you stress you knowledge that this is a known defect of the camera). They may also include free shipping both ways (free shipping varies with countries). This is regardless of your camera's warranty status. Please see this link for more info.

Affected cameras with this problem include: A60, A70, A75, A80, A85, A95, A300, A310, S1 IS, S60, S230, S400, S410, S500, SD100, SD110, IXUS V2/V3/300/400/430/500/II/IIs, IXY Digital 200a/300a/320/400/450/500/30/30a