An ISO 4217 Currency Code must be three characters long; your value is
The above error is what I'm getting in trying to pull SalesOrders between start and end timestamps. The exception shows up in the exception view as 'There was an error in the XML document at (1, 766).' but after opening it and drilling into the inner exception you see the currency code note.
Searching the error message in Google will yield the following MS article about duplicate ISO codes, which GP itself allows but Web Services doesn't allow.
https://support.microsoft.com/en-us/kb/924546
Now, I went into Tools > Setup > System > Currency and checked each code, writing it out as I went and looked for duplicates, found none.
I checked [DYNAMICS].[dbo].[MC40200], which really just shows the list I saw in the UI, verified no duplicates.
I checked [BRICK].[dbo].[MC40000] and the only entry was my Z-US$ and it had the matching index id, etc from MC40200. All looks good there.
I'm stuck now as I don't have any other reported reason why I should be getting this error.