WindowsMediaPlayer Lag Issue

Recently, WMP has started to lag when a video is being opened.
This could be when i try to open a video, or i am streaming one off of a webstie that uses WMP as its player.
The problem only occured recently and nothing in particular would have possible triggered the problem.
When a video is opened, or simply WMP itself, it freezes up and lags my whole computer making it un-useable.
I wait for all of about 20seconds, and then it returns to normal and plays the video fine.
Yet if i close and reopen the player, the same issue occurs.
I have the latest version of WMP, 11 I think, and all my graphics drivers are fully up to date.
I have a fairly high spec computer, Q6600, Gefore8800GTS 640MB, 4GB DDR2 RAM.
The problem occurs every time WMP is opened, whether many program are open in the background or not.
Please advise.
Thanks,
Sabre_X