MOUNTAIN VIEW, Calif. (AP) ¿ Hansen Medical Inc. said Monday it will restate financial results because of potential errors in registering revenue from sales of the company's Sensei Robotic Catheter system. The medical robotics technology company plans to restate results stretching back to first quarter of 2008. It said some of the errors came from outside its accounting department. Shares fell 32 cents, or 9.3 percent, to $3.11 in morning trading. The stock has traded between $2.44 and $11.88 over the last 52 weeks. The Sensei systems are used to properly place catheters in the heart during surgery. The company shipped 68 systems through June 30 for which revenue was recognized and it received full payment for all but two systems. It did recognize a partial payment of $320,000 on one of those two systems. "An investigation by Hansen's audit committee, with the assistance of independent outside counsel, has identified systems for which revenue should have been recognized in a later period than the period in which it was recognized and revenue on a smaller number of systems that should have been reflected as deferred revenue on Hansen's balance sheet as of June 30, 2009," the company said in a statement.