vimでinsertすると改行される

centos6.10でvimを使用しています。TeraTermからSSH接続をしています。
vimを起動して文字を挿入しようとすると、一行目が消えてしまいます。
（正確には上にスクロールすると一行目はあるのですが、なぜか方向キーで一行目までいけない）
設定しなおしたりしましたが治りませんでした。
vimをアンストしたほうがいいのでしょうか。

set nocompatible
set encoding=euc-jp
set fileencodings=iso-2022-jp,sjis
set fileformats=unix,dos
set backup
set backupdir=~/backup
set smartcase
set incsearch
set number
set list
set showmatch
syntax on
highlight comment ctermfg=LightCyan

if v:lang =~ "utf8$" || v:lang =~ "UTF-8$"
   set fileencodings=iso-2022-jp,sjis
endif
set fileencoding=euc-jp
set nocompatible        " Use Vim defaults (much better!)
set fileformats=unix,dos
set bs=indent,eol,start         " allow backspacing over everything in insert mode
"set ai                 " always set autoindenting on
set backup              " keep a backup file
set viminfo='20,\"50    " read/write a .viminfo file, don't store more
                        " than 50 lines of registers
set history=50          " keep 50 lines of command line history
set ruler               " show the cursor position all the time
set number
set showmatch
set wrap
" Only do this part when compiled with support for autocommands
if has("autocmd")
  augroup redhat
  autocmd!
  " In text files, always limit the width of text to 78 characters
  " autocmd BufRead *.txt set tw=78
  " When editing a file, always jump to the last cursor position
  autocmd BufReadPost *
  \ if line("'\"") > 0 && line ("'\"") <= line("$") |
  \   exe "normal! g'\"" |
  \ endif
  " don't write swapfile on most commonly used directories for NFS mounts or USB sticks
  autocmd BufNewFile,BufReadPre /media/*,/run/media/*,/mnt/* set directory=~/tmp,/var/tmp,/tmp
  " start with spec file template
  autocmd BufNewFile *.spec 0r /usr/share/vim/vimfiles/template.spec
  augroup END
endif

if has("cscope") && filereadable("/usr/bin/cscope")
   set csprg=/usr/bin/cscope
   set csto=0
   set cst
   set nocsverb
   " add any database in current directory
   if filereadable("cscope.out")
      cs add $PWD/cscope.out
   " else add database pointed to by environment
   elseif $CSCOPE_DB != ""
      cs add $CSCOPE_DB
   endif
   set csverb
endif

" Switch syntax highlighting on, when the terminal has colors
" Also switch on highlighting the last used search pattern.
if &t_Co > 2 || has("gui_running")
  syntax on
  set hlsearch
endif

filetype plugin on

if &term=="xterm"
     set t_Co=8
     set t_Sb=m
     set t_Sf=m
endif

" Don't wake up system with blinking cursor:
" http://www.linuxpowertop.org/known.php
let &guicursor = &guicursor . ",a:blinkon0"