Unkillable process: what does this PS command output mean?

This process couldn't be killed. I tried kill -9 and it's still hanging on by the skin of it's teeth: What does ?E mean in the status column? I think I have a systemic problem with this on my Mac but I'm struggling to diagnose it!

$ ps -efl | grep -i juc
  501 12992     1   0 Fri01pm ??         0:00.00 (Projucer)           6086   0  0        0      0 -      ?E                  0

I can't attach a debugger to it either:

$ sudo lldb -p 12992
Password:
(lldb) process attach --pid 12992
error: attach failed: Error 1

Also this non-exiting starts to affect all the processes:

501  1548     1     6084   0   0  0        0      0 -      ?E                  0 ??         0:00.00 (Skype)          Wed11am
  501  3017     1     6004   0   0  0        0      0 -      ?Es                 0 ??         0:00.00 (com.apple.appki Wed01pm
  501 12992     1     6086   0   0  0        0      0 -      ?E                  0 ??         0:00.00 (Projucer)       Fri01pm
  501 36351     1     6004   0   0  0        0      0 -      ?E                  0 ??         0:00.00 (TMHelperAgent)   4:11pm
  501 37977 37926  1006006   0   0  0        0      0 -      ?E+                 0 ttys000    0:00.00 (lldb)            5:36pm
  501 38053 37997  1006006   0   0  0        0      0 -      ?E+                 0 ttys004    0:00.00 (lldb)            5:39pm