After much thinking I just fixed how to fix the install of mist of pandaria ( when you often stuck at 25% or 75%)
also when you have install problem in the launcher.
1. Download this : <Snip> ( this is a complete paste of MoP beta map )
2. Open in "Winrar" (if you dont have it, install it) .
3. Paste the "World Of Warcraft Beta" map in to your Harddrive.
4. In the map "World Of Warcraft Beta" map open "WoW.exe".
It should pop up a windows that should complete installation
5. Now Mist Of Pandaria Beta should start!!