the filter graph manager won't talk to me

[BlueToast]

I do not know what I did lately, but now I can't open any AVS file in MeGUI, and MPlayer won't play even the simplest of scripts.

This is the error MeGUI gives me:
AviSynth script error:
DirectShowSource: RenderFile, the filter graph manager won't talk to me
(D:\Network\Videos\LEELAND1.avs, line 1)

LEELAND1.avs

DirectShowSource("D:\Network\Videos\LEELAND1.MOD", fps=29.970, audio=false, convertfps=true)
Load_Stdcall_Plugin("C:\Program Files\MeGUI\tools\yadif\yadif.dll")
Yadif(order=-1)
#crop
#resize
#denoise


If I try to open LEELAND1.MOD, I get the same error (except without the third line in the error message). I know I used to be able to open these files just fine a month ago!

EDIT :: I have reinstalled AViSynth and ffdshow Tryouts, and I have replaced my DirectShowSource.dll with the one available through AViSynth site.

I did install Nero 9 a week ago. Might this be in the way?