Ideas ? (Besides the usual support-desk-guff ?)
Well, I checked my main TOAW 3.4 directory (I made loads of copies of betas as they rolled out). In the main dir, along with opart 3.exe and all the language dll's, I have TWO serial reg text files -
serialreg lists the serial number for 126.96.36.199
serial.reg lists the same serial number for 188.8.131.52
To me, they look the same except for the version number. Do you have both in your directory ? (I do not know if you need both, but I'm guessing with an upgrade, the 'dot' version is added.) If you have only one, maybe try cloning the missing piece -- it's the same block of text, just the different version, and the different name. Shutting the PC down, and bring it up and trying again.
HTH or at least rules out this as the problem.