|If you have an option for safe mode with ethernet, then you will have access to cable or other high speed internet connection.|
MORE IMPORTANT: If you can open in safe mode, SAVE your files! If the computer is going, and you do not know if the hard drive is going or not, this may be your last chance to save your files!!! Save to removable medium like CDr disks or USB flash drive (or USB hard drive).
When your files are secure, it is time to figure out the problem. First check RAM with Memtest (create a bootable floppy or CD), and test your hard drive by downloading utility from your hard drive mfg.'s web site (and create a similar bootable disk). Then post back results.