Plasma televisions may be subject to nearby magnetic interference; so, any unshielded stereo speakers and other electronic devices should be moved a minimum of 2-3 feet away from the TV. If the source of the problem is indeed magnetic, the spots can appear ether small or large and will normally be red, green, or blue. On the other hand, similar to LCD televisions, what you might be seeing could be a few of the many pixels that make up the composition of the plasma screen - however, plasma technology differs from LCD technology . There may be a few pixels (or small dots) that do not change color; they may appear red, green, blue, black or white. If it appears to be a problem with pixels, the issue may possibly be corrected by performing a power reset .
If the issue is still unresolved, service may be required. Begin the procedure to send your Sony product into a Sony facility to be repaired.