Found a similar issue and solution in google groups
I opened a windows command prompt and ran the command
$ tasklist
It looks as though the ssh connections I had made in my git bash shells weren't being closed when those windows were closed and were hanging the available git bash shell windows.
This may be a dangerous solution but from the windows command prompt I ran
$ taskkill /F /IM ssh.exe
Everything appears to be working again after this. It may not have directly been an issue of orphan processes, but this worked for at least for me.
Additional note: you can also kill other processes, for example like:
$ taskkill /F /IM vim.exe