"Took out the particle effects as it seems to lag over the internet :/" Particle effects are perfectly do-able using applets, but for it to work without lag you'll have to make the images static so you don't reload them every time you use them - my guess is this was where your lag was coming from.

Can't reproduce the above situation personally but I'm not surprised it happens from the description - it's a classic bug in Greenfoot pong / breakout / ball / block style games. The problem usually occurs when you don't put a special case in for the ball contacting the left or right edges of the block - so it tries to move as though it hit the top of the block, and as a result usually either bounces up and down very quickly in the block or "sticks" to it for a while (depends on the implementation.) The solution is to add a check in when the ball hits the block to see whether it's hitting the edges (shouldn't be that hard, just check the ball's x position relative to the block's position and size) and add in the appropriate special behaviour - such as bouncing it to the side rather than straight up.

If it's just a simple Greenfoot.delay() you want to put in, have a look at the started() method in World - this is called whenever execution starts. So if you simply override it and put a delay in there, I would've thought this would have the effect you're after :-)