vim - In gvim, change inner word (ciw) puts me in insert mode midway -

why happen in gvim:

• i'm in normal mode, , want replace word, "bat".
• i place cursor on "t".
• i try type 'ciw', press "i", goes insert mode , enters i, such word becomes "bait".

am in special mode? works fine in regular vim.

do other commands work fine? then, it's bad mapping on c. can check with

:verbose nmap c 

from description, sounds have :nmap c ii.

alternatively, can start gvim without personal config , plugins:

$ gvim -n -u none