Hi, Chasing a vfork issue in emacs prevening on sub-shell or dired on a uptodate cygwin install, i followed the FAQ and tried to do a rebaseall. Unfortunately, that resulted in a core dump with the rebase.exe.statckdump mentioning a STATUS_ACCESS_VIOLATION problem! I then also noticed, that an update with the latest version of the setup.exe also causes a rebase.exe.stackdump in c:\cygwin64!. Subsequent attempts rebasing in safe mode or after re-installing everything (via setup and click on All until it says re-install) had the same problem, as did upgrading cyginw, cygwin-debuginfo and cygwin-devel from the current 2.4.1-1 to 2.5.0.4 :-( [The vfork problem in emacs, though, did disappear ..] I have cygwin running via a few months and didn't change anything in the config recently (although i did run setup to update to latest version). Unfortunately, i have no idea when setup also caused to coredump on rebase. It might have done it already for a while but as it doesn't complain, i have no idea when the rebase.exe.stackdump started showing up in c:\cygwin64. I googled for this problem but couldn't find any references to rebase itself failing. Anybody has an idea what's going on and/or how to debug or work around? -michael- PS: I'm running cygwin on Win 8.1 (64-big); see attached cygcheckout for more info.