TMPGEnc author4 running codec twice

[BRck]

Hi everyone, looking for some help here.

I was using a Toshiba notebook (model A135, 1GB RAM, dualcore 1.73, video Intel 950, downgraded to Windows XP) to author my DVDs with TMPGEnc authoring Works 4 with K-lite codec pack, and it was working just fine, flawless.
I've just traded it for another Toshiba notebook, this time an A305 (core 2 duo 2.02GHz, 4GB RAM, ATI Radeon 3100), running Vista-64.
Here's what's going on: all softwares play videos normally (WMP, MPClassic, etc, Toshiba DVD MovieFactory); but in TMPGenc, when it's in 'edit chapter' function, there's this stuttering playback and it keeps getting slower until it stops responding. A normal DVD task (render/burn) that used to complete in 2h now takes 5:50h in my new 'powerful' notebook.
I don't know it this is the problem, but it's strange: in TMPGEnc when it enters edit chapter mode, it seems to open the ffdshow codecs twice (I mean, it shows two icons for ffdshow video and two for ffdshow audio - the other programs only show one of each as expected).
There's a setting in ffdshow config to check for multiple instances running, I've set it to "only one", but it keeps opening twice.
I've already uninstalled K-lite, installed a newer version, same thing. Now I'm using CCCP codec pack and it's just the same.

Please, any suggestions I can try? Is this a vista-64 issue?
I don't want to lose TMP, but the OEM Toshiba MovieFactory 5 is working better now, but it's too basic for my needs.

[Baldrick]

have you tried disable ffdshow completely? wont it read the source video then?

[BRck]

Yes I did that, and it didn't read the video.

I've just tried DVD MovieFactory 6 plus and it worked fine, but it doesn't have all the features of TMPGEnc.