blue / purple

[scrim]

I have got 2 avis (1 movie) and have normally being splitting each one in tmpeg. Gives good results 9 times out of 10, but end up with 4 cd's, I wanna get 3 cd's Also i think the nero is causing my odd jumpy svcd and therefore wanna burn with fireburner.
With this in mind have been informed to try nandub, to merge the 2 avi's, then run through dvd2svcd.
Now the problem
The avi is fine ,good quality , but once it has been ran through nandub, the colour goes to pot, get a lot of blue / purple , though not all the time ?
This is the same as when i play a xvid avi. But when the xvid avis are ran through tmpeg , this always sorts out the colour probs.
Sadly ,not the case with this file ?
Also gives the same results through VDUB (thinks ,will check that again ?)any ideas please. Not sure if it is divx / xvid etc.. as it doesnt say in the filename TIA

[scrim]

ok , lets simplify this
When i input a superb quality avi file into virtual dub (or nandub)
the movie colours go all purple and blue.

If i run the avi straight through tmpeg, it is all ok.
Have all obvious codecs installed.

reason i am doing this
1. I want to merge 2 avis into one so that
2. i can run through dvd2svcd and get 3 images as the end result.

reason is because i thik nero is making some mpg2 files jumpy when burning, and wanna make images instead, to burn through fireburner.

Am i totaly going about this the wrong way ???