I purchased the Canon SD300 / IXUS 40 a few days ago and then bought two Integral 1GB SD cards; one for my PDA and the other for the Canon. I have, however, been experiencing "memory card error" messages at no-particular interval.. i.e I can be shooting around 30-200 images and then when its time to play the images back via the camera a "Unreadible Image" message will be shown; and no amount of left-right clicking will move on to the next image.. and no sooner do you turn it back to picture-take mode than you get "memory card error" .. This is all confounded by the fact that your sometimes able to see the images in picture-view mode..
I have given the card a deep test on both the PC (with scan-tools, checkers, etc..) and also in the PDA and it works perfect. The images are even still contained there and can be pulled off with ease both via my PDA and PC card-reader.. but as soon as I stick it back in the camera, bang .. error messages. Sometimes I can't even format it, but can do so via the PC or PDA.. again, no problems.
I wonder if this camera has known issues with memory cards over a certain size / speed..? -- and I can't blame the SD card as it works with both the PC & PDA..
I have been in contact with my supplier and they have agreed to replace it with another - but I'm very concerned that its going to be the same issue again.