He has been chairman of the Norwegian Banks' Guarantee Fund,[1] the Norwegian Industrial and Regional Development Fund,[3]Mediehuset Vårt Land[4] as well as the corporate council and election committee of Statoil.[1] In late December 2002 he became chairman of the Southern Norway Regional Health Authority.[5] His tenure was marked by turbulence. The chief executive Steinar Stokke had to step down from several hospital boards in May 2003 because of a flawed project where patient diagnoses was to be coded in different ways to be eligible for public funding.[6] In January 2004, Arntsen tried to oust Stokke from the executive chair, following the "coding case" as well as roundhanded pension deals with company executives. Arntsen was supported by deputy chair Helen Bjørnøy and board member Ole Johan Sandvand, but was voted down by the rest of the board (Kaare Norum, Einfrid Halvorsen, Anne Mo Grimdalen, Terje Keyn, Morten Falkenberg and Svein Øverland). Arntsen subsequently had to resign, but in response, the Minister of Health Dagfinn Høybråten promptly relieved the entire board of their positions.[7] Stokke resigned the next month.[8]