Today I am having a problem with Apache restart. It is continuously giving me the Unclean shutdown of previous Apache run error. After googling for two hours I got a answer to it. Actually I had installed a Skype on my system which uses port 80 for its some connection purpose and Apache also uses it. So simple un-check the Use port 80 option in the Advanced -- Connection tab from Skype options. Then restart the apache it works well. Hope it works for you as well. What a stupid mistake.