There is a simpler (and correct) explanation for that

They say when there are 2 possible explanations for a particular event, the simpler of the two is usually correct. I got a first hand experience of that recently.

My trusted 4 year old Canon A520 all of a sudden started showing signs of old age. 4 years should not be too much. My first digicam, a 2.1 MP Kodak, which was the bleeding edge of gadgetry when I bought it, is still alive, though it is doesn't like to come out of the cupboard for the fear of being insulted by my cell phone camera.

I noticed 2 problems: The batteries started getting drained out too fast and the camera once in a while showed "Error E30" on it's display. Immediately the engineer in me started looking for a complex, grand explanation for this. Out came the multimeter and confirmed that the batteries had correct voltage. A torchlight confirmed that they had enough juice too. Canon says "Error E30" is related to SD card. I formatted the cards. I also read that the lens barrel could have some obstruction, which could result in the camera assuming that there was not enough power in the batteries to push the lens out. I wanted to disassemble the camera to clean the lens barrel and I found detailed instructions on a website to do this. However, I just could not get the outermost ring of the lens barrel out and hence I decided to take the camera to the service centre.

The service centre told me that my camera was alright, in spite of all that I had read. They said the batteries were indeed at fault. I did not believe this initially, but since they demonstrated with their batteries, I had to oblige. I bought some new Sony 2700mAh NiMH batteries and this solved all the problems with my camera. Now I know that there is neither a problem with the lens barrel, nor with the SD cards. The problem was that I had tried to save some money on my previous set of batteries by buying a not so well known brand. The problem was much simpler than I had expected! I later read in various forums that that bad batteries could indeed cause these problems. However, initially my mind was looking for a fancier problem, so I had ignored all this!