My Ixus has been acting up and I stopped using it, I got memory card errors on my 256 MB sandisk so I switched to my 128 MB sandisk but got the same errors !!! reformatting helped but after a while the menu system did not let me get to the reformatting !!! I gave up and let the camera be for some months but now I neede it but got the same stupid errors finally I remembered that I still had the canon 32 MB CF which came with the camera so I tried it and everything started to work again !!! and now it works fine with the 256 MB as well, very strange I think.

Have you tried getting the local priest/religious person to exorcise the camera?

No need, the magic canon CF fixed it all