I have encountered this a few times now.
Attempting to merge several posts where as least one of the posts has a like, results in a server error.
The behaviour can be tested with these 2 posts:
http://xenforo.com/community/threads/ips-bites.10197/#post-138907
http://xenforo.com/community/threads/ips-bites.10197/#post-138909
And these 2:
http://xenforo.com/community/threads/jack-russell-terrier-thread.9852/page-2#post-134805
http://xenforo.com/community/threads/jack-russell-terrier-thread.9852/page-2#post-134806

Attempting to merge several posts where as least one of the posts has a like, results in a server error.
The behaviour can be tested with these 2 posts:
http://xenforo.com/community/threads/ips-bites.10197/#post-138907
http://xenforo.com/community/threads/ips-bites.10197/#post-138909
And these 2:
http://xenforo.com/community/threads/jack-russell-terrier-thread.9852/page-2#post-134805
http://xenforo.com/community/threads/jack-russell-terrier-thread.9852/page-2#post-134806
