Each page zone has its own list of stations.
Does the HG contain a list of individual stations or an extension list? If it has an ext list it may be your culprit; if not, keep looking (if its a bunch of individual stations instead of an EXTENSION LIST, they'd only ring one at a time. Look through each Call Routing Application under Digit Translation, make sure none have that HG pilot as destination. Check DIDs (call routing tablles), make sure no destinations are that HG. And check Extension IDs and Mailboxes in voice processor, make sure none match HG number. Last option, delete the group, which will kill its connection to anything else, then recreate if you really need it (remembering to put the HG back in anything that needs to point to is such as recall destination.