VIM Syntastic error for HTML5 - html

Question

I'm a newcomer to VIM and installed GVIM successfully on my Windows 8.1 laptop. I uploaded the Syntastics plugin using Pathogen and, as I'm planning to write an ionic project, I also copied the tidy5 for html5 binary (from http://www.htacg.org/tidy-html5/) and referred to the binary in my VIMRC as follows:
" SYNTASTIC
set statusline+=%#warningmsg#
set statusline+=%{SyntasticStatuslineFlag()}
set statusline+=%*
" automatically load errors in the location list:
let g:syntastic_always_populate_loc_list = 1
let g:syntastic_auto_loc_list = 1
" check on errors when a file is loaded:
let g:syntastic_check_on_open = 1
" check on errors when saving the file:
let g:syntastic_check_on_wq = 0
let g:syntastic_html_tidy_execute = 'C:\Program Files (x86)\tidy-5.1.25-win32\bin\tidy'
let g:syntastic_shell='C:\Windows\System32\cmd'
" check debugging messages in vim with :mes:
let g:syntastic_debug = 1
let g:syntastic_mode_map = {"mode": "active",
\"active_filetypes" : ["html","javascript","json"],
\"passive_filetypes" : ["html", "javascript","json"] }
When I run
:SyntasticInfo
I get the following output
Syntastic version: 3.7.0-76 (Vim 704, Windows)
Info for filetype: html
Global mode: active
Filetype html is active
The current file will be checked automatically
Available checkers: -
Currently enabled checkers: -
For some reason, my default checkers aren't loading, and when I run
echo syntastic#util#system('echo %PATH%')
I get a E484 error
Error detected while processing function syntastic#util#system:
line 9:
E484: Can't open file C:\Users\Dirk\AppData\Local\Temp\VIo8366.tmp
-1
I suspect there are multiple issues here, so I assume the first one I need to solve is the E484 error. Any help appreciated.