In CS5 and CS5.1 respectivly (two different pc's) when increasing brush size of the various tools, part of the circle indicating the brush size dissapears, in essence leaving the full O for a small brush and only seeing a part of the brush "circle" with larger sizes.
Depending on how much the brush size is increased it may be anywhere from a half to quarter circle visible on the image file. Actual brush size in pixels is dependant on image size, for example an 800 x 1000 pixel image might be at 50 pixel brush size, while a 2400 x 3000 px image, the issue would occur at say 120 pixel brush size, which i'm thinking would be a direct relationship to brush/image size as opposed to a random occurance.
I've also changed various brush options in preferences to no avail.
Is this simply a CS5/5.1 oddity that one needs to live with?