MJPG decompressor Windows 7 64bit

[um3k]

I'm running Avisynth sEt's multithreaded AviSynth 2.60 build on Windows 7 64-bit, and have run into a problem. When I try to load a video file from my old digital camera, I get the following error message:

"AVISource: couldn't locate a decompressor for fourcc mjpg"

I've tried installing MainConcept and Matrox MJPG codecs to no avail. Here's what MediaInfo says about one of the video files:
General
Complete name : C:\Users\Justin\Pictures\photos\2003_10_15\Picture0029.AVI
Format : AVI
Format/Info : Audio Video Interleave
File size : 48.8 MiB
Duration : 3mn 0s
Overall bit rate : 2 274 Kbps
Mastered date : Sun Sep 28 01:46:03 2003
Writing application : CanonMVI01

Video
ID : 0
Format : M-JPEG
Codec ID : MJPG
Duration : 3mn 0s
Bit rate : 2 183 Kbps
Width : 320 pixels
Height : 240 pixels
Display aspect ratio : 4:3
Frame rate : 15.000 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 1.895
Stream size : 46.8 MiB (96%)

Audio
ID : 1
Format : PCM
Format settings, Sign : Unsigned
Codec ID : 1
Codec ID/Hint : Microsoft
Duration : 3mn 0s
Bit rate mode : Constant
Bit rate : 88.2 Kbps
Channel(s) : 1 channel
Sampling rate : 11.024 KHz
Bit depth : 8 bits
Stream size : 1.89 MiB (4%)
Interleave, duration : 1000 ms (15.00 video frames)
Interleave, preload duration : 1000 ms
Here's the script I'm using:
SetMemoryMax(512)

Import("L:\Avisynth\SuperRes\NoMoreMoire_a4.avsi")

first=AVISource("C:\Users\Justin\Pictures\photos\2003_10_15\Picture0013.AVI")

first ++ BlankClip(first,length=15) ++ AVISource("C:\Users\Justin\Pictures\photos\2003_10_15\Picture0016.AVI") ++ BlankClip(first,length=15)\
++ AVISource("C:\Users\Justin\Pictures\photos\2003_10_15\Picture0029.AVI") ++ BlankClip(first,length=15) ++ AVISource("C:\Users\Justin\Pictures\photos\2003_10_15\Picture0030.AVI") ++ BlankClip(first,length=15)\
++ AVISource("C:\Users\Justin\Pictures\photos\2003_10_15\Picture0037.AVI")

NoMoreMoire_alpha4(j4i=true, intermode="nnedi3", mcmode="hybrid")
The error refers to the first AVISource call, so it doesn't relate to the number of sources. This script works perfects fine on my XP 32-bit PC, so I'm baffled as to what is going wrong.

Any suggestions?

[Inspector.Gadget]

You ought to be able to use ffdshow, provided you install the VFW decoder and set it to decode MJPG.

[um3k]

I'm pretty sure I've tried that as well, with no luck. I'll try it again, though.