My brushes in PS7 aren't working right

I know this doesn't really have to do with icons but I really need some help.

Last night I was in the middle of making an icon and I needed to use a brush. I clicked on the brush button and when I went to aply a brush to my icon it showed a cursor that looked like this . So it makes it really hard to tell where my brush will show up on the picture. I tried it again this morning and it did the same thing. I closed photoshop and then reopened it and now it's back to normal. It's been doing this on and off for a while. Does anyone know why this happens?

Sorry, if I'm not making too much sense.