SV got screwed by the US Gov't when it came to reequipping the airline. The MD90 order was part of the Airbus vs US + Gulf War formula that also left KU with 1 747-400, a few A310s, 777s, 4 A340s, 2 767s etc.
Apparently the software on the MD90 is so useless the aircraft has had to be stopped on the taxiway and shutdown and 'rebooted', just like with your PC. McDD executives from the 'final days' should offer refunds for producing a line of completely unuseable aircraft, and apologise for besmirching the name of a once-great company.
(As you can see I am in quite a belligerent mood due to having a horrendous cold for the second week running.)
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz