Here's the correct link -
http://www.archicadwiki.com/Bugs/SpellCheckerCannotInitialize
Although this was already correctly set on my machine but was still failing!
But - I think I may have found the trigger for this as I noticed it was failing on an existing project, but not an new project with a small bit of text pasted in.
If you have an @ (at) symbol on its own in any text field, the 'Cannot initialise MSWord' error will occur.
Try a simple test for me to confirm - create a blank new project, create some text WITHOUT an @ in, and run the spell check. It should run fine. Now add an @ symbol separated with a space from the other text. Re-run the spell check : error will occur!
Interestingly it doesn't occur if the @ symbol is next to another letter like in an email address e.g. peter@; only on its own!
The problem on mine was probably triggered from the titleblocks on the Masters. They all had the scale written as '1:### @ A3' on!
Hopefully this is the problem, and can be quickly fixed.