There is a problem with the option to Approve All Pending Members in the Members Pending page. To fix it, around line 451, admin_accounts_pending.asp, find this code:
MP_MemberApprove = allApproveData(mMEMBER_ID,RowCount)
Replace it by this:
MP_MemberApprove = allApproveData(mM_APPROVE,RowCount)