negative iteration numbers in .ext files

Does anyone else have the 'feature' of negative iteration numbers in the .ext file that nonmem writes? Mostly the values are similar or identical to the preceding lines but not always (see example below). I am using nonmem 7.1.2 with gfortran 4.5.0, installed with nmqual 7.1.0 on Windows XP. Thanks for any clues. Andreas TABLE NO. 1: First Order Conditional Estimation with Interact ITERATION THETA1 THETA2 THETA3 THETA4 ....OMEGA(10,10) OBJ 0 2.70000E+02 7.00000E+01 7.00000E+00 3.00000E+00 0.00000E+00 17903.085422267555 10 2.62990E+02 4.41321E+01 7.48823E+00 4.16453E+00 0.00000E+00 17596.998988682855 20 2.30575E+02 7.98655E+01 7.36614E+00 1.19184E+01 0.00000E+00 17573.820822902107 30 2.31353E+02 7.94068E+01 7.36395E+00 1.17636E+01 0.00000E+00 17573.797569595510 40 2.31992E+02 7.88078E+01 7.38680E+00 1.16398E+01 0.00000E+00 17573.754599870816 -1000000000 2.31992E+02 7.88078E+01 7.38680E+00 1.16398E+01 0.00000E+00 17573.754599870816 -1000000001 1.27442E+01 1.15823E+01 1.56697E-01 3.27570E+00 1.00000E+10 0.0000000000000000 The information of this email and in any file transmitted with it is strictly confidential and may be legally privileged. It is intended solely for the addressee. If you are not the intended recipient, any copying, distribution or any other use of this email is prohibited and may be unlawful. In such case, you should please notify the sender immediately and destroy this email. The content of this email is not legally binding unless confirmed by letter. Any views expressed in this message are those of the individual sender, except where the message states otherwise and the sender is authorised to state them to be the views of the sender's company. For further information about Actelion please see our website at http://www.actelion.com