Sorry about posting in the wrong forum I don't believe I can move it, so if a moderator happens across this please move it to a better home so that others may benefit.
Yes, the above was from the DNP audit log... I later found the event log as well, but thank you for noting that here.
As it turns out, my event log didn't show anything either, but through trial & (lots of) error I eventually found what was preventing the accounts from creating. I never did find out what caused the problem in the first place other than that it seemed to be tied to a specific time frame where every account we created during that time was "damaged".
In my case the results of the damaged accounts where components of the hosting account which DNP either couldn't, or wouldn't delete. I have DNP create an AD account, setup an FTP space and create a folder for the user. Some of the affected accounts had created new folders with a "1" appended apparently in an attempt to work past whatever it was having trouble with, but others were just sitting there as if nothing was wrong.
To fix my problem I just had to delete all traces of the account's existence beyond DNP. In other words I had to erase the actual user from my server, erase the FTP space AND erase the directory itself. I tested every combination of leaving any one of those pieces behind and every attempt failed except when I deleted everything. Once I purged all of that I was able to manipulate the account as it should have been again with no errors. Fortunately we were able to identify the damaged accounts and recreate only those necessary but as I write this I still have a few to go.
In the end the only "real" problem was that DNP never sent back an error condition when attempting to create these damged accounts. We create all of our accounts from our billing software as a front-end to DNP and that software received "everything OK" back from DNP, but everything was not OK because DNP had created the account partially and then reversed the process when whatever unseen bad thing happened. Technically the account was created, but then it was immediately purged without telling us. We found out the hard way when things just didn't work.