Okay, mention some nasty bugs you've hit are and in what game that bug was in.
I just hit one in Dungeon Siege 2, myself, In Act 2 Chapter 8 w/ the battle w/ Talon.
[spoiler]I saved in the game when I met him, but I quit....so I exited the game so I can take him on later. So, when I decided to go back to the game and loaded my save and made my way back to him, he no-showed.
Talked to the commander hwo gives you the quest -- and went back to Talon's location. No dice; he wasn't there. Great.
And this is a main quest, so you have to defeat him to go to the next part.
And since GPG hasn't fixed this quest in a patch, I might have to use a 3rd party hotfix to move on. Wonderful.[/spoiler]