HyperBBS uses its own Home stack. It's very important to keep them straight and not try to use the regular Home stack with HyperBBS or open other, non-HyperBBS stacks, when using the HyperBBS Home stack.
The HyperBBS Home stack contains most of the HyperTalk scripts that make the BBS run. It also contains a set of XCMDs for talking to the serial port. The main purpose of the HyperBBS Home stack is to keep from having to reproduce these things in all of the various stacks that make up HyperBBS. But some of the scripts make changes to cards and fields, and therefore can muck up non-HyperBBS stacks.