Could be something wacky with the actual media player and not SVP.
Try a fresh copy of MPC-HC Portable from here:
http://portableapps.com/apps/music_vide … c-portable
And follow the very basic SVP configuration instructions for MPC-HC here:
https://www.svp-team.com/w/index.php?title=SVP:MPC-HC
If that doesn't work, try enabling "D3D Fullscreen"* in that copy of MPC-HC Portable, close the program, and then re-launch it.
*You can find this setting in "View" -> "Options" under "Playback" -> "Output", but make sure your "DirectShow Video" is set to "Enhanced Video Renderer (custom presenter)" or the checkbox for "D3D Fullscreen" will be greyed out.
If that doesn't work, then it could always be the actual video file itself. Are you using the same exact video file that worked a few days ago?