Win2k3 Forest Trusts

[synectics]

I was having a read on this topic http://www.msfn.org/board/index.php?showtopic=53506 but I have a little more in depth issue with that suggested configuration.

Overview

We have an existing Forest of domainx1.com and a newly created forest of domainy2.com.

domainy2.com is for a hosted service, mail + web and previously only existed as dns records and pointers within domainx1.com. But we deem the requirement for this hosted service to be contained within its own forest.

I want to establish a forest trust with these domains. according to the above hot linked topic it tells you to setup dns forwarders etc between the domains. But domainx1.com already had dns records for an existing domainy2.com domain therefore it cannot be created as it already exists in the forest

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DNS

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The server forwarders cannot be updated.

The zone already exists.

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OK

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..but without this, the forest trust cannot be established.

The only trust I seem to be able to create is a realm trust. (both domain and forest are running in win2k3 native mode)

Has anyone any suggestions? Or has encountered a similar issue? Its driving me mad...