Cliff Notes at the bottom**
Hopefully I can figure out what's wrong. I've read the K-Lite codec package FAQ and have tried everything that I can think of.

I have a problem where when playing video files (mostly avi, but it happens on all video files), and I go to fullscreen by double clicking on the video screen while playing, it seems to stutter, and takes a while for the video to actually go to full screen. And even then, it's a choppy transition. The audio will continue playing, and when the video actually gets to fullscreen, it plays in a faster speed as if to catch up to the audio. After it catches up to the audio, the video resumes normal play. During the stuttering/choppiness time, My "Yahoo! Widget Engine" widgets also flash rapidly. This also happens when the video file is double clicked in an explorer folder which opens Media Player Classic to play.

I never had this problem when using Media Player Classic as an independent program, and using ACE Media Codec Pack.

I've tried using all three 2.80 version K-Lite Packs, and the problem persists through each. I have also updated the 2.80 versions with the 12-6-2006 update.
The K-Lite FAQ states:

Q: The video stutters a lot when I play it fullscreen
A:

This can be a result of certain graphics card settings. Try changing the following settings in your graphics card control panel:

- Set FSAA to 'Let the application decide'
- Disable anisotopic filtering (AF)
- Disable antialiasing

I have a laptop, and the only graphics options I can tell only allow me to toggle "anisotopic filtering".

**Cliff notes:

K-Lite Codec Packs installed (basic, standard, and full, one at a time)
Media Player classic
While video file playing, double click to go to widescreen and video stutters.

Is this a problem where there are codecs interfering with each other? I uninstalled ACE Media Codec Pack before ever installing any of the k-lite codecs, is it probable that there are some codecs on my computer that interfere with k-lite that I may have not uninstalled? Does my problem indicate symptoms of this?

If you go fullscreen, then the player won't just suddenly use different codecs. If it was a codec problem, then you would have problems during normal playback as well.

This is a driver problem.

Changing the output renderer in Media Player Classic options might solve your problem.

When first opening the video file, it stutters as well. I'll give a look around in MPC options. Thanks for the reply.

Well what do you know? Under the Output/Directshow Video options, I selected system default and problem solved as far as I can see. Thanks for the help!!!

Before, it was set to "Overlay Mixer".