Internal Error MMX state left on:

Have you tried any other MJPEG codec? 

Any other, previous, version of Morgan MM? How about PICVideo? with PICVideo you can get RGB or Force YUY2 output. (I don't know if this is possible with Morgan MM?) Could your problem be related with a colorspace conversion, internal to the codec?

This suggestion might be completly off track but I have experienced problems with long file names when using W98. Maybe you could try using the short filename of "Fira 80 Bday_01281984_2.avi" or just rename it to something shorter.

Is VobSub installed? I saw in another thread, that it might create problems.

@juanc This avi was encoded with is the latest MM mjpeg V3 codec. Not sure if you can force YUY2 output? It has a settings window (via control panel, sounds sand multimedia) where I can choose a few things, such as float vs integer for decompression. I attached an image of what the settings look like if that helps. I tried both float and integer with no change to end result. However I think it may be the MM mjpeg v3 codec decompressor partially responsible. I tried opening up a different avi with divx encoding and it works with vdub with no problems. Does this explain why I can play the original avi in vdub with dierctshow source since it uses a different decompressor? I'm a newbie at this so please let me knwo if you think I'm on the right track. Even if it is the MMJPEG, regardless of which avi I'm using (divs vs mjpeg) I still can't open an avs with in CCE any longer, which is a really big pain right now. Is there a way to completely uninstall and reinstall all video codecs? I have installed the following programs or codecs previously: divx 4 and 5, windvd, windows media player, MMmjpeg V3, vfapi support, other codecs (microsoft, indeo, cinepak, etc..) @dvd2svcd I'm using windows 2000, but I also thought of this earlier and changed the filename to fira with no change in result. BTW, thanks much for your prog I use it constantly and I'll use this as a reminder to donate some more to your excellent efforts.

VobSUb is installed 

Yes I have vobsub installed. I can uninstall, but I have had it installed for the past 3 months and I've been using avisynth extensively with no problems.

If you have an older version of Morgan MM codec, give it a try. Uninstall the current one and test the avs with the older. Also make sure that only one avisynth.dll is floating around in your installation.

Figured it out