Premiere Pro either crashes on exporting media file, or the file isn't playable... gah

Hi, I'm having a problem exporting a file. It's the first time this has happened in over 50 exports I've done in the past. The first time I tried exporting it, it seemed to have worked. The video thumbnail looked like any other successful video thumbnail with a screen shot from one of the frames. But when I tried playing it, it would play smoothly until around the 7 minute mark (it's a 17 minute video). After the 7 minute mark, the video would lock up. I found it strange and tried restarting the computer and playing it again but to no avail. I was using the internet while file was being exported so I thought maybe I somehow screwed up the process by overloading the computer, although according to my CAM, RAM load never ever even gets close to 100%. I think at most, it's like 30 or 40%.

Second time I tried exporting, I left the computer be. I just let computer use all its energy on exporting... but this time, Premiere Pro actually crashed around the 60% mark. It had a message that said something happened... I forgot what it said, but basically, I had to shut it down.

So I shut the PC down again, restarted the export, and this time, the export finished without crashing Premiere Pro, but when I went to look for it, I found that the thumbnail was just a generic movie reel icon, as opposed to a screen shot of one of the frames in the video, which is the norm for playable videos... So when I went to view it, it popped up this message:

"This file isn't playable. That might be because the file type is unsupported, the file extension is incorrect, or the file is corrupt."

I don't know what the problem is... my latest guess is that maybe my hard drive is too full. Currently has 64GB freed up, and the file I'm trying to export is 32GB, so technically there's plenty of space, but maybe it's still too close to the limit, giving the hard drive fits. I don't really know why my hard drive is so full... it's just my programs, really. I could probably free up around an extra 60 or so GB just deleting older videos I previously exported to desktop; I usually export to desktop and then transfer it to an external drive before deleting it from desktop. I'll try exporting directly to an external drive this time and seeing if it's any different.

Please let me know if you have any solutions. Thanks.