Smooth Flowing Water Technique with S3?

I know this question may sound cliche but I'm still very new to photography. I've never tried working on flowing water before but have read in various books and magazines on how to achieve the soft flow of water. What I did was that I switched it into Manual Mode and started trying out different Shutter Speeds with the Aperture of F2.7. I couldn't quite get what I wanted because futher lowering my shutter speed only causes an overexposed shot.

I changed my aperture to F8.0 and worked with a shutter speed of 1/30. And that was the lowest I can get too to obtain a balanced shot (without blown highlights on the water). Any lower than that only overexposes my shots! The motion of the water still appeared pretty harsh to me and I wasn't happy with the results. I wanted to change the exposure but being in Manual Mode, I couldn't do that. I tried switching to Tv but S3 seems to have a mind of its own - when I tried a shutter speed of 1/5 it turned automatically to 1/40 before I hit the shutter! Is this a camera defect?

I didn't know how else to get the smooth flowing effect of water, got frustrated and left the place. I didn't tried any other modes after that. What did I do wrong? What do I need to do to achieve that smoothness? I distantly remembered something about "locking the AF/AE point" or something similar. Has this got anything to do with my problem? I'd really appreciate it if someone could enlighten me on this. =)

Thank you.

You need a Neutral Density filter. That will allow you to get an exposure of 7-10 seconds or so. That should blur the water nicely.

Smaller aperture, longer shutter speed.

If you can't get the shutter speed low enough, you might need some neutral density filters.

Try shooting when the sun's low in the sky.

I too think you should try an ND filter. As far as your other question about the camera being defective because it changed your setting. You have the safety shift on. Look up safety shift and you will understand more about it.

I don't know much about the S3 and what you can and cannot do. I also don't know what settings you were using for the shots, but if you lowered your ISO (if you can do so with the S3), then lowering it will make it so that more light is needed than at a higher ISO. Therefore, lowering your ISO to say ISO100 will need twice as much light as the same image in ISO200. Consequently, you can open your shutter up longer to get the desired effect.