system stuck while reboot/shutdown-Collection of common programming errors

some body help pls. ive searched damn a lot and read other similar questions. i have ubuntu 13.04 64bit on Dell inspiron n5110. it crashes when i when rebooting or shutting down. happens very frequently, let’s say, once in every 5 shutdowns. some times it stucks in terminating processes, some times in stopping modem manager and other things. i removed speech dispatcher and edited “GRUB_CMDLINE_LINUX_DEFAULT=”quiet splash” line. it didn’t help.

i also had boot problems, i mean stuck before booting up. it was solved by removing grub and using neosmart boot loader.

thanx for ur help in advance