I suppose I should offer an explanation . . .

When you mark a component as 'Required' or similar every method call will enlist any applicable providers into a transaction. So if you have a SQL Server referenced in a function call (highly likely) that SQL Server will be enlisted, as will the file system, and the source-code itself.

Win2k3, by default, prevents MSDTC from enlisting providers across the network - for obvious reasons I won't go into here - but the basic premise is that MS-RPC (which MSDTC is derived from) is not a very secure subsystem, so MS lock it down by default.

What I suggested to you is to navigate to the tickbox that allows you to override the defauly MS settings regardin enlisting providers across the network.