Hi, I hope someone can help. I painted my downstairs toilet and have small cracks all over an area of about 2 foot square. Originally I painted a white Dulux under coat before putting on some B&Q bathroom paint. The paint finish was good but the wall surface was uneven - so I did a bit of sanding and adding polyfilla to get a flatter finish and repainted. These small, dark cracks appeared - at first I thought I'd got particles of dust / hair in the paint. I resanded and repainted -all looked good but when it dried the cracks reappeared through the new coats. Today, I did the same - same answer. I then sanded a little further and put polyfilla 'fine' for hairline cracks over the cracked paint. I sanded this lightly so the cracks were no longer visible and then repainted. I did this over a bigger area - I thought the finish looked great an hour or so ago but have just looked and I have these damn cracks all over the area I've just worked on. I have never seen this before - is it the paint (I've never used B&Q before - but the problem is only on a small area - not the whole room). I'd really appreciate anyone's advice because my only other thought is to re-sand back to bear plaster and start again (and cross my fingers) but I am not certain that would help given my experience so far..