I'm not really sure when it started but I noticed the other day that my phone appeared to have lost root. I tried to reroot using z4root and I had to reenable USB debugging. This worked fine and I had root back...

...until I disabled USB debugging! I thought this was only necessary to get root and once it was setup, no longer needed. I'm sure I have had debugging disabled since I rooted.

Anyway, it's reproducible: enable USB debugging, root works; disable USB debugging, root doesn't work. I've tracked it down to an issue with su (obviously?). Using a terminal emulator, when USB debugging is disabled, su hangs. Issuing CTRL-C does result in the root # prompt though, so it is working.

The only thing I can think is I updated Superuser to 3.1.3 and the binary to 3.1.1 but I don't knwo if it's related to that. Has anyone seen this issue before? I'm tempted to roll back to an earlier su binary but I don't know where to find it?