Click the Windows icon in the bottom left corner of the screen or press the Windows key on your keyboard and start typing 'pokertracker' and you'll see the option.
See the tutorial kraada linked for more information about log files.
If you play at MicroGaming (MPN) then the invalid pot sizes is a known issue. If you want a notification when the fix is released please open a Support Ticket
That would also explain the duplicates due to the way that MPN stores its hand histories - you can prevent this by using the 'Clear databases now' option in Configure > Sites & Import Options after your session.
If you're not playing at MPN please attach one of the hand history files which causes the problem to your ticket along with your log file.