Downloaded ac3 filter & U-lead MF2



I successfully used MF2 with a downloaded ac3 filter on my previous desktop (XP Pro). I have now invested in a laptop (with XP Home), and it appears that MF2 does not recognise the ac3 filter (which I have copied over)- the message box comes up every time I import an mpeg file into MF2, which I have always doen without any problems before.
Does anybody know why it should be any different on different PCs?