I had been away for more the half an hour.
What I came back to was 100% CPU usage.
Threads at a constant 147
Almost all of my 512 Meg gone.
I thought there may be some thrashing as the
page file was up to 13%.
I started a memory freeing program.
I eventually set it to free 40 Meg when 7Meg was left.
Then I watched the creep about 1K/sec. until the limit is hit.

May be related to the not flushing of data to disk.
I did check

I havent ruled out all other programs yet but there
is only one recent adition
My upload is now well over 1.2 Gig while my download is
only at 900Meg. !!!!!

The threads situation is known; 1 thread per (sub)directory shared is created.

What version are you using? 1.09 had major problems indexing. 1.11 seems to do it fine. (no CRC checking)

Check the other threads concerning lockups or CPU usage for symptoms and possible causes. (I don't feel like typing it all out again.)