Dirt on Sensor?

I've noticed that on most pictures I've taken with my NEW 30D, I see a small shadow or speck on most of the pictures. Oddly, it is not on Every picture. For example, in 2 pics taken only 20 secs apart, one shows, the other doesn't. I see the spot on 3 different lenses, so I assume it involves the camera. Posting little images of the spot I see at 3 difft focal lenghts on the 3 lenses.
Does this provide inof to determine the cause of the problem?

Do I have to drag myself back to the dealer to fix this, or get a new camera, or what should be done?

Thanks

The third upload in next thread - this was weird since it shows two spots - looks like a shadow of itself?

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here are 2 more per above

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It is probably dirt on the sensor, which is very common and can usually be taken care of with a few blows from a Rocket Blower. You probably see it at higher F numbers. Check the various threads and internet articles on sensor cleaning, and try a blower before anything else.

You need to take a test shot a f/22. If using Windows XP open up Microsoft Paint to a blank page and fill the viewfinder using manual focusing on the lens _ take a shot.