Hi,
Follow the steps in the links below: Stream your media to devices and computers using Windows Media Player:**http://windows.microsoft.com/en-US/windows7/Stream-your-media-to-devices-and-computers-using-Windows-Media-Player**
Change settings for streaming media in Windows Media Player:**http://windows.microsoft.com/en-us/windows7/Change-settings-for-streaming-media-in-Windows-Media-Player**
Also you may try to temporarily disable Anti Virus and check if you can get the option to play to and play it on your Play Station 3.
To share you must have under 'Network and Internet' a 'Homegroup' set up with share pictures etc. with devices checked. You must also have under 'Network and Media Center' 'Share with Media Devices' the Local Network set to 'allow all'. You can easily access these via WMP12, if you look under the drop down list 'share', it's the bottom two items, just select those to go to the relative panel.
Any media you wish to share should be stored in the folder 'Libraries' under the relative category. For some reason, videos can only be accessed from selecting the 'Folders' on the PS3, if you select 'All videos' only the sample wtv file in recorded tv samples shows, which
Hope it helps.