I have the same problem when converting from DV to MPEG when using TMPGenc. I was encoding a series of clips. Half of them came out perfect. Then I installed some codecs. All of the answers from people in this forum say its the angelpotion codec.
I finally found instructions on how to uninstall it on the web. They are as follows for Win2000:

To remove AngelPotion under Windows NT/2000:
Open regedit, drop down to
HKEY_CURRENT_MACHINE\SOFTWARE\Microsoft\Windows
NT\CurrentVersion\Drivers32, and delete or rename these
keys:

Key name Value
VIDC.AP41 APmpg4v1.dll
VIDC.DIV3 APmpg4v1.dll
VIDC.DIV4 APmpg4v1.dll

However I don't have any of these keys or values in my system. I think its another codec that is causing the problem.

Can anyone help us?