This is all second-hand information so apologies if I make any mistakes. I thought it might be useful to pass on what I heard:
Jon mentioned that he made another test version which removed the shell-folder-lookup code completely so that it was like 1.6.2 in that area. (i.e. Removed the code which was moved around in the patch.) That version worked okay on Rusty’s machine.
The version based on the patch, which still fails on Rusty’s machine, seemed to work okay on the machine of another user who was having problems before. But Rusty mentioned that while the crash still happened it happened less often. so perhaps the second tester didn’t use TortoiseSVN as much or in the same way.
It’s possible there’s something else on Rusty’s machine which is perturbing things but the crash dump for the patched version apparently shows a memory corruption around the code accessing the critical section in the patched area, which seems like too much of a coincidence. (This is different to the original crash dump which showed a deadlock over a pair of critical sections.)