Q: Hi my mac was full and showed a message your start up is full, when I shut down my mac it started up then closed before completing the start up few sec after I typed the pass code and it's not starting

Try booting into Safe mode

<http://support.apple.com/kb/ht1564>

Then free up space on your system

First look for some easy low hanging fruit in your home directory and your Downloads folder

Once you have some room to do things, try using

OmniDiskSweeper (free download)

<http://www.omnigroup.com/more>

When using OmniDiskSweeper, or any utility that shows all your files...  See the following article if you want to run it as root

<http://www.macobserver.com/tmo/article/how_to_recover_missing_hard_drive_space>

Boiler Plate Warnings:

If you have a recurring, running out of disk space, problem, then OmniDiskSweeper may help identify where the space is going.  Posting the suspected locations and files will help the forum help you to figure it out.  Remember, we cannot see into your disk, you have to give us information to work with.

DO NOT delete files in your Home Folder -> Library tree as there are things like your iPhone backups, your email messages, your application preferences, etc…  If you think you have found something in your Home Folder -> Library that can be deleted, you should ask first.

DO NOT delete files outside your home folder, as you may end up deleting something essential to Mac OS X, and turn your Mac into an expensive “Door Stop”.

I will point out that you will find some very large files in private -> var -> vm (these are the Mac OS X virtual memory paging files (swapfiles) and where Mac OS X stores the copy of RAM when your Mac is put to sleep).  The swapfile(s) get deleted on reboot, and the sleep image is just going to be created again when you put your Mac to sleep.

If you think you have found something to delete outside your home folder, it would be best to ask first before deleting.  There are many examples of people deleting files outside their home folder, or renaming files, or changing the ownership or file permissions, and then their Mac stops running.  Do not be one of those people.  Ask first.