It still isn't quite clear. The exact error and exact steps are needed, but you can debug this yourself as well.

run a trace on the 2000 server and watch what is called when the user connects with Management Studio. It's possible there is still a permissions issues since SSMS might make a different call.

I haven't heard of this particular issue with SSMS connecting to 2000, but not many people try to give access to jobs.

The other option is to grant access to sysjobs and sysjobschedules and let the users access information through scripts.