
Her profile is the same as a previous user who was able to post.
Any insights?
2 answers

Hi,
Only group owners, group managers, and users with the “Modify All Data” permission can post and delete group announcements.
https://help.salesforce.com/apex/HTViewHelpDoc?id=collab_group_announcement.htm&language=en_US (https://help.salesforce.com/apex/HTViewHelpDoc?id=collab_group_announcement.htm&language=en_US)
So, try to set that user as the group owner or group managers.