I have been using Photoshop Elements 9 for more than a year, and recently I have been experiencing a glitch/malfunction of some sort with the color picker and hard mechanical brush tool.
As you can see in my example above, there are two things wrong: 1.) When the brush is painted, little grey crescents appear between the individual strokes of the brush. These appear even when I do not release the mouse button when painting. However, it only happens on a specific layer, and not on any other layer - in this case the layer entitled 'skin'.
The second malfunction is the color picker/foreground and background colors. As you can see, the foreground color selected in the example does not match the last color I painted (color splotch to the far left). The color that was actually painted was a far more saturated version of the selected color. Again, this only occurs on the 'skin' layer as well.
(My brush settings are: Fade: 0 Hue Jitter: 0 Scatter: 0 Spacing: 1 Hardness: 100)
Though these "glitches" are occurring often recently, I have found a temporary solution. Switching to another layer, then painting on it, then switching back to the malfunctioning layer seems to temporarily rid me of this issue. Yet and still, I would appreciate any permanent solution suggestions.