Is it just me or is everyone having problems with this game?

For the last 4 or 5 days it just won't play properly - I don't do techy speak so the best way that I can describe it is that its just all "jerky". 

It my fave game so can someone please help.

My game is not jerky but the "playground" has shrunk and is so small that playing is difficult - the gaming area used to be much larger. Is that just my PC or has the same happened to others?
There are also other minor flaws - and I have problems with Java, too!