Some days ago I had dust on the mirrors of my 350D/Digital Rebel XT.

I tried to remove it, only obtaining to have more dust on them.

The result: when I used the camera again, the dust went from the mirrors to the sensor, with this effect:

 

I was hoping this wasn't visible at high aperture, but it isn't so... :-(

I need your help: did you had this problem and how do you managed to resolve it? (Please, specify if it is a direct or indirect experience!!)