Hi Mike,
The reason I specifically suggested taking it from simMarket is because Word, Wordpad, OpenOffice Writer and suchlike add control characters in which, although you can't see them normally, can mess up what you are actually inputting as your information to the registration page. simMarket's "My Products" page lists them in a code box that is specifically ASCII only to avoid these errors, hence that being the best place to get them from and guarantee that they are error free.
The other thing you could try is copying yours from Word into Windows Notepad (not Wordpad, specifically an ASCII only text editor) which will remove any control code and then copying and pasting from there, but that doesn't rule out any errors that were transposed into the Word file when you created it.
As I said before, FSUIPC keys don't time out, they aren't machine specific (I've transferred mine numerous times) so if you are having a problem, it's not because the key is no longer valid.
Unfortunately Pete is away at the moment (there's an announcement at the top of the forum that says when he'll be back - I can't view multiple windows from the mobile browser, sorry!) but beyond that I'm afraid you'll have to get more support from him when he gets back.
Cheers,
Ian P.