Incomplete download/when does Gnotella write to disk?

I have encountered this a few times, but last night was the most frustrating... I use Gnotella to transfer large files. In this case I have been accessing a 70 meg file. A few days ago, I was transferring the file and got 36 megs of it. I resumed the transfer and noted that the file was not getting any bigger on my hard drive. Experimentation showed that this occurs on resumes, but if, during the resumed session, I abort, the file is appended to whatever I had downloaded. Question 1: Where does Gnotella store the data before it appends it to the file or am I just seeing an artifact of file locking? Ok, I tried for days to finish this file transfer and finally got it going last night. I stayed up and baby sat it for the duration of the transfer. It completed.. and about a minute later, I lost power to my home. When I got rebooted, I looked at the file and it was back to 36 megs! Question 2: I appears that the file gets written when an abort happens, and usually when it is completed... why would it not be written upon completion this time?