There is probably a better way than digging through the file-system. I'll share what I know. Hopefully somebody smarter knows a better way.
1) Check for duplicate running processes
If you had the same process running multiple times, that could create the conflict that you described and you might be able to stop here.
if you know the process name, then try:
ps -ax | grep <name-here>
2) Make sure that the package is really uninstalled:
If you run the command below, you'll see that it's not installed or you'll see the corresponding files that are still on your system.
dpkg -L <name>
If you had a few package with similar names, you could do the following:
dpkg --l | fgrep <name>
Once you found what the package was, you could then use the first dpkg command to find all of the files associated to it.
3) Reinstalling and then searching
If you wanted to search through the file system directly, you might not find results right away. Because the package might be partially uninstalled with pieces of it left behind, you might have to know exactly what you're looking for or re-install and then actually view all of the directories and files it touches. You might try reading the man pages on find. Just know that it's not hard, but it's also not straight forward like locate.
4) Package maintainer
You could type the following:
apt-cache show <name>
This is neat for two reasons. If there is a package currently installed, it will show the package twice. The top one is available and the bottom one is the installed version. You may find some information that can lead you to the package maintainer.
I'm hoping one of these will get you up and running until you find a nugget or get a better solution.