I too find quite unstable to use the run package task within a DTS and use the Jobs instead to chain the DTS.
For portability reasons, I do not let the standard command string in the job, I replace it with the command line generated by DTSRUNUI so the job refers to the package name rather than the ID.
This makes easier the task to move jobs to another server using a script.
I also use a network alias rather than either Local or Machine name.
Example, in the SQL Server Client Network Utility, i create an alias i.e "Datamart" that point to the machine I want. i have the same alias in all machines. I use this alias in all packages, jobs and connections so they will allways resolve to the machine I want. For servers, it is the local machine, for dev boxes, I manipulate the alias so my dev instance will take data from the server I want.
Last but not least, I use DTS Backup 2000 to move DTS packages from server to server and i use the server's DNS name in the OLAP Cubes connections or Query connections so if I change Production Server, I simply swap the DNS entries and all user's queries now repoint to another machine without the user's knowledge.
Take care, Philippe