Hello,
You are getting an "Address already in use" error. That means there is some other "afni -niml" process running on that computer (possibly by you, but it could be someone else).
First ask for an available NIML port block, and then apply it with -npb. So consider these commands:
afni -available_npb
(and supposing this says "2" is the first available npb)
afni -npb 2 -niml
3dGroupInCorr -npb 2 ....
Does that seem reasonable?
- rick