This has been a bug since the first builds of vista over 3 years ago...
Try this media player and see if you can play everything ok (link) :>
'Media Player Classic - Free Software Downloads and Software Reviews -
Vista has two versions of WMP you can try these codecs available from
(link) 'FileForum | Vista Codec Package x64 Components'
They are for the *X64* version of Windows Media Player... This version
has to be manually configured to run instead of the x32 version by
default. Use this Guide for infomation on how to switch the version of
wmp (link) http://tinyurl.com/278asb
Open Windows Media Player and right-click the thick black bar in *a
empty*-space and goto the Tools-menu and open Options then click the
*Performance* tab, down the page under DVD and Video playback tick Drop
Frames to Keep Audio And Video sync
Media Classic should good good or the only other solution is change the
file properties and tick the box to disable "desktop composition" if all
the other methods dont work