WMPlayer 11 vid playback freezes, then speeds up

I've been having a bit of an issue running HD content.



Recently, I've been running many 1080p .mkv video files in Windows Media Player 11 with the help of the K-Lite codec pack. Last night though, one particular video was playing normally up until a certain point, when suddenly the video froze for a couple of seconds, followed by it speeding up to catch up with itself. All the while, the audio track continued as normal.



Any reason why this may have happened? It's been stumping me all night. Is there perhaps, another, more superior media player I should be using? (Media Player Classic and VLC both gave me inferior performance, by the way)



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System Manufacturer/Model Number

Asus G73JH-A1

OS

Windows 7 64-bit

CPU

Intel Core i7 Q 720 @ 1.60 GHz

Motherboard

N/A

Memory

8 GB RAM

Graphics Card(s)

ATI Mobility Radeon 5870 w/ 1 GB VRAM

Sound Card

N/A

Monitor(s) Displays

1920x1080