I'm no computer techie, but I'm assuming when you complain of the computer slowing and rebooting, perhaps you have a RAM leak, ie. it takes forever to open other programs or check your email after BitTornado has been running for hours. Perhaps windows isn't re-freshing its memory properly so that when it runs out, it just reboots itself or at least cuts some of its processes off (ie. blank screen).
I get system slowing if a torrent has been open for a long time, especially if the downloading file is larger than 2GB.
First, I tried checking the box "flush data to disk every 5 mins" under prefs, and that didn't seem to help.
Next, I clicked on advanced and hit "finish allocation" at the bottom, even though I was only 0.1% done. Right away, BT made a file the size of the finished download. You are going to use the space anyways, so why not allocate the amount you need right away?
Interestingly, after almost 19 hours of downloading a 4 GB file, I am finding my system is as fast as if I just booted up! It's still d/l at 80K, too.
I hope this helps some peeps!