Photoshop brush opacity problem

[Jomahun3]

Hi all!
I have a problem, whenever I try to make a brush stroke it comes out 50% transparent. The brush opacity is set to 100% and the layer is also set to 100%, and the mode is normal. I reseted the brush tool, but it didn't help at all. Basically I didn't change anything, but somehow the brushes and the paintbucket are not working properly. Do you have any idea?
Thanks in advance!

[Steve]

Make sure your video driver is up to date.

You can try to uncheck Enable OpenGL Drawing in preferences.

Try resetting the preferences file.
When that gets corrupt a lot of strange things can happen.

Start Photoshop and immediately hold down Ctrl+Alt+Shift (Windows)
or Command+Option+Shift (Mac OS X).

Then, click Yes to the message, "Delete the Adobe Photoshop Settings file?"