Green dotted line.

[Jim]

Hi, I'm new to Gimp and was doing brilliantly until my brushes stopped working.  The 'marching ants' in the active window have been replaced with a dotted green line.  I`ve spent several hours trying to correct this. Can anyone please help?

[rich2005]

Could be that there is still an active selection somewhere, even a single pixel that you do not notice. Make sure selection is off. Select -> None

Another possibility is trying to paint outside the active layer. The yellow dotted line is a layer boundary. Shows when the layer is active.

There is a pixel lock for each layer, toggles on / off Paint tool will have a 'barred' icon next to it and a message in the notification area (bottom of the window)

Trying to paint on a non-visible layer?  The brush will have a 'barred' icon next to it and a message in the notification area 

   

None of those? Please post a screenshot of the whole gimp window showing layers and tools options.

[rich2005]

Try again Jim, leave a message this time