Ok, I've done as suggested above (stop services, un-install, re-install, restart services), but still have the same issue whereby the Domain accounts config dialog is truncated across the bottom...
Interestingly, while troubleshooting this - stopping the services, performing a 'repair' from the add/remove programs option & then after the services restarted, I can see the 'full' dialog - good news! Funnily though, still not working & internet connection no go...
Logged off the server > logged back on
Now, when I try & check the domain accounts using the config tool, it is truncated again..
I'm going to do the following in an effort to fix - stop services > uninstall > remove user accounts & ass'c folders (C:\Program Files (x86)\SolarWinds\Orion > all subfolders) > reinstall > fingers crossed...