"No Memory Stick" errors

Due to the length of the memory stick it rarely causes bent pins sideways but they can over a long period lose their tension and fail to make contact with the memory. Also, more commonly they can tend to get a build up of dirt on them. Try using an old memory stick and quickly push the stick in and out of the camera as fast as you can and do this for about 15 to 20 times (with the camera off of course) this should clean any gunk built up on the contacts. Now switch on and use the new stick to see if it's working. If not try the exercise again. If it still doesn't work try sticking 2 layers of sticky tape to the front (the side opposite the gold contacts)Run the tape from the bottom (the contact end) to the top. Running it to the top will ensure it comes out with the stick when you eject it and it doesn't stay inside causing problems. Doing this will marginally increase the size of the stick and put a little more pressure on the contacts. Just nake sure the sticky tape comes nowhere near touching the stick's contacts as this will tend to make them pick up dirt. Also this trick is only to see if it's you camera's contacts have lost tension, its not meant as a permanent fix. If neither of these tricks work I'm afraid it's a trip to the camera hospital.

Normally when a memory stick is inserted the wrong way or in a speed, the contacts pins inside the cmera tends to bend. If the camera is not sensing the stick this may the problem.

All the other suggestions are great advice. I went all through them and then remembered what happened with the camera a couple of years ago. The camera sometimes seems to be sensitive to a lowish charge. Even if the charge is sufficient to get the machine starting up as nornal sometimes it seems to need batteries with a really good level of charge, perhaps because the contacts are damp or dirty. I found that my battery charger wasn't working properly and as soon as I borrowed someone elses charger it all started working instantly.