Have found a bug which is causing the problem. Try running project "problem" online (http://scratch.mit.edu/projects/Davidgpa/34476), the ship'x x position=290.
Run it on the PC (ie development mode) and it = 274.
Running using the htm code suggested at "http://scratch.mit.edu/forums/viewtopic.php?pid=790#p790" gives the online value (as it should).
Any ideas guys ?