Soft Brush gradient/banding/pixelated all of a sudden??

[TooDarnLoud]

I just saw a picture i'd posted online and noticed that i'd forgotten to smooth off a hard line - simple semi-opaque brush gradient usually does the trick to hide those lines. Anyway, went into Photoshop, turned Smooth edges on in the Preferences (I had it set to nearest neighbor for some pixelart I was working on). But now the brushes seem to just look really weird and like it isn't 'flowing' properly - far away the gradient seems to just cut off, and kinda pixelated and banded up close. Also, using the brush at 50% opacity it seems to be closer to 10% opaque.

I have been using this copy of photoshop (CS6) on the same monitor for as long as i've had both (and the monitor is virtually brand new). This problem seems to have only just cropped up now.

Examples best viewed at full size, if possible. its a little tricky to see, but in the second set the brush appears to have a small, soft "core" and then gradient around it looks like a kind of bleedy airbrush sort of effect. I've seen a couple of posts about this, but ive not seen any definitive answers. I'd really appreciate some help!

[davescm]

Can you try the brush at it's default 25% spacing and see what it looks like

Dave

[TooDarnLoud]

Sure, it's more or less the same. I forgot to mention in my original post, but it also seems to be affecting the gradient fill tool too. It seems to be something about the transparency that is causing problems. As you can see below, it seems to be bleeding into whatever is underneath it. (i hope you can see it okay, it seems to be a lot darker posting it on here)

[davescm]

I'll be honest and say I am struggling to see the issue in that last screenshot.

See below 2 100% opacity strokes with black, round brush 81 px, 0% hardness 25% spacing viewed at 100% zoom . They look the same as yours.

Dave

[TooDarnLoud]

Yeah it is hard to see, but If you see my brush strokes at full screen there is that weird grainy effect that isn't normal. I think it's actually something to do with the opacity settings rather than the brush itself - the problem in my last reply is that It's doing some weird bleed where the colors seem to 'join' the shape of what is underneath it. If you look at where the black meets the green it kind of 'curves out' to pool together with the green brush, rather than remaining a constant gradient