There is a known issue with HELM 3 with Frontpage extension that the Frontpage user not able to login if the account have been recreated through the HELM system.
This is because the fp_ prefix user is not added correctly, to resolve this issue, you may refer to the step as below.
1) Login to the server using Terminal Services Client
2) Open Computer Management
3) Go to Local Users and Groups -> Groups
4) Expand the description field. Look for the group that contains the domain name that was readded the in the description field. The group name will end in _AdvAuthor. Double click this group
5) Add the domain_fp user to this group, click OK.