Microsoft said Thursday that it is <A HREF="http://news.zdnet.com/2100-3513_22-5958553.html?tag=zdnn.alert">searching for a new leader</A> for its Microsoft Business Solutions unit, which sells software to medium-sized businesses. Doug Burgum, who has had financial responsibility for the division, will remain in a new role as chairman of the unit. However, the software maker aims to recruit someone else to oversee the unit's financial performance. In an email to Microsoft staffers, CEO Steve Ballmer praised Burgum's work and the performance of MBS. The unit is a money-losing business, but has seen its sales grow in recent years.