Hi , we have an issue … we are playing a game called contract wars on FB and this game was working fine but yesterday some of us become unable to play the game … a download message popup asking us to download UnityWepPlayer … we did this but the problem didn’t gone and all games that need UnityPlayer not working now 
i did the same as here about 15 times but nothing works
http://docs.unity3d.com/Documentation/Manual/TroubleShootingWebplayer.html
and here is the log :
131122 01:21:14 ------------------------------------------------------------
131122 01:21:14 Instance starting, version 4.3.0f4_e01000627d60, UNITY_WEB_ENABLE_AUTODOWNLOAD: 1, GetDisableAutoUpdates(): 0
131122 01:21:14 Datafile https://a2-40-so.ssl.ucdn.com/kg/WebPlayer/WebPlayer.unity3d?v=134555953446
131122 01:21:15 Setting error display: 'Failed to update Unity Web Player', details: 'A newer version of Unity Web Player is required, but the auto-update download failed.
Was trying to download https://ssl-webplayer.unity3d.com//Channels/7eed886c2a59/UnityPlayer3.x.x-win32.zip', link: 1
about my PC :
CPU : I5 2500K
GPU : GTX 660
RAM : 8 GB
sorry for my bad english 
and when i go to : Unity Real-Time Development Platform | 3D, 2D, VR & AR Engine … on right screen i see : “not installed” !!!
please help
I get this problem all the time when playing Battlestar Galactica Online. I’ve posted about this but never get a response.
Guess they ignore “newbies” here.
@owstetra - the game you are playing appears to be made with Unity 4.1.5f1. Last week we shipped the Unity 4.3 version, and announced to web players that there was a 4.3 version of the plugin available. As gamers updated to this version we noticed an increasing number of crashes, so then decided to put these users back to 4.2. The intention is that all games should now have the 4.2 plugin on their machines. It’s possible that you got caught up in this reversal. My advice would be to uninstall the plugin, and try re-installing. I know you say you have tried this. The plugin, and the data files it needs, are usually installed into your AppData/LocalLow/Unity/WebPlayer folder. It might be interesting if you can let us know what version number is written into the loader/info.plist and player/3.x.x/info.plist files. The player and mono folders are only present when you have viewed Unity content, and we usually recommend when troubleshooting that you view content from the Unity gallery before doing anything else.