The next thing to check is that there is not any internet protection software blocking LOGic from using the internet. Try turning that sort of stuff off temporarily. But you'd think if that was the case other things would not be working either.
I would go thru the process manually and see if that turns up anything.
http://www.hosenose.com/...ing-LoTW-and-LOGic.aspx
Also, 500 is a common server error. I would call ARRL and see if anyone else has reported any 500 errors.
At what step in the process does the 500 error occur? When uploading the TQ8 file I would assume....
Let me know.
Tnx/73,
DH