start -up & shutting down freezing
 

i have problem on my laptop during start-up process & shutting down because most of the time its suddendly unresponsive,totally freezing & the only way to get back to its normal state is when rebooting it by hard reset.
i have Acer aspire 5750 12.04 (Precise Pangolin) 64bit, 4 Gb ram, Intel HD graphics 3000. I had noticed after updating my system on
available updates the following day the said error will occur., please guide me what appropriate updates
should be done only in order to avoid the problem.

Start by checking if you can boot and shutdown your machine OK in runlevel 3. If runlevel 3 shows errors too try runlevel 1. Then check your system logs for errors. If unsure post them here, if there's a lot to show then please attach a plain text file instead or pastebin it.

Its too late spawn..i reinstall it yesterday. I believed the problem was frequent updations i made because since i updated it last two months i encountered these sudden crashes,unresponsiveness..i fail to revert it also since too many issues to track down & im worried maybe it will damage my system sooner thats why decided to reinstall.. thanx for your time..