In the data directory is a file called ADSPROF. One of it's purposes is to locate the Currency Files; MCCODES.LD4 is one such file. The problem likely is that your ADSPROF file is pointing to a place where currency files indeed exist, but not the same ones you had been using before - with the CDN and/or DOS code created. The error message you are getting indicates the currency code it wants to find is CDN.

The solution is to see if you have the 'currency code' group of files still around. Search for the file name MCCODES.LD4, and it and about a half-dozen other file (MC*.LD4) will exist in the same dirctory. It's a matter of finding the 'old' ones, and copying them to the \softrak\system directory - where you likely set the path when first setting up the data.

Hope this isn't too confusing...