I've had this problem before with V4s (composite signal only). When the run gets super long the engine within the v4 can't process the color anymore, and it turns into just black and white. This can be verified with a local monitor on the 2nd out of the V4, it has nothing to do with resolume. The fix is to use a distribution amp that actually gains up the signal, not just splits it such as http://www.kramerus.com/products/model.asp?pid=497&sf=3
Kramer 101L, optimally at the camera, or alternatively, just in front of the v4.
When it happened to me, I got basically this information from Roland support. Good luck.