Restart Problem-- Won't let me boot my computer up anymore.

Question

I downloaded an update, and it prompted me to restart my computer. When I did, this error message comes up, and it won't let me reboot my Macbook. It just stays on this screen, no matter what I do.
I've also tried to re-install OSX by using the original boot disks, but I get the same screen each time. Here are links to the screen I get each time I reboot.
error message:
http://s132.photobucket.com/albums/q23/z3nbrain/?action=view&current=screen1.jpg
the second one is of the full screen, but the error message is the same: http://s132.photobucket.com/albums/q23/z3nbrain/?action=view&current=screen2.jpg
Is there anything I can do to get around this? I've a lot of files on my HD that I'd like not to lose, but I'm afraid my only option is getting a new HD or a completely new MB. Btw- If I can't figure out how to do this myself, I'll be taking it to a Genius Bar-- will they be able to fix this problem, or would it require me to actually ship my laptop directly to apple?

Answer 1

This is unashamedly lifted directly from MacFixit.com - hope it helps
"Problems starting up after Apple's February 15th updates (Security Update 2007-002, DST, Java R5): Fixes
Yesterday Apple released a slew of system component updates via its Software Update mechanism and as standalone downloads yesterday, including:
* Security Update 2007-002
* Daylight saving time update (2/15) for Mac OS X 10.4.8 and 10.3.9
* Java for Mac OS X 10.4 Release 5
* Java for Mac OS X 10.3 Update 5
Several users are experiencing relatively serious issues after applying these updates, including startup stalls, repeated kernel panics at startup and more. Unfortunately, since Apple released the updates simultaneously and many users applied all the updates in a single session, it is difficult to decipher the culprit(s) in most cases. It should also be noted that the updating of specific system components may not be strictly at fault in some instances -- instead, the update process itself may introduce issues or uncover preexisting problems [See this article on direct and indirect causes of issues after system updates for more].
That said, there are a few common workarounds that prove highly effective in resolving the most prevalent startup issues post-system-update, as follows:
Disconnect external devices/internal cards Try removing any FireWire, USB or other external peripherals then re-attempting startup.
Failing that, try removing all PCI cards, ExpressCards or any other internal hardware that did not ship natively with your Mac.
Disconnect network cables The cause for delay in some instances of this issue may be network related -- as Mac OS X tries unsuccessfully to ping an active connection. Temporarily disconnecting any ethernet cables -- then re-connecting them once Mac OS X has started up -- may resolve the delays.
Delete Caches/.plist files If you experience startup problems, first try starting in Safe mode (hold the "Shift" key while you startup), then delete some cache and .plist files to make sure their corruption isn't at fault.
This can most easily be accomplished with a shareware utility like Tiger Cache Cleaner or Panther Cache Cleaner, but also bears a manual process which involves dragging the following files to the trash:
* com.apple.kernelcaches (a folder in /System/Library/Caches)
* Extensions.kextcache (a file in /System/Library)
* Extensions.mkext (a file in /System/Library/)
* com.apple.ATS (a folder in /Library/Caches/)
* com.apple.loginwindow.plist (a file in /Library/Preferences/)
* Files that start with com.apple.LaunchServices (in /Library/Caches)
You will be prompted to enter your administrator password when dragging these files to the trash. You may need to restart after moving them to the trash.
Check for problematic login/startup items Startup in safe mode (hold the "Shift" key while you startup))
Next, go to the Accounts pane of System Preferences and click the "Startup Items" tab. Select all the login items and click Remove, then restart.
Also, check the /Library/StartupItems and /System/Library/StartupItems folders and remove any third-party items.
Look for problematic kernel extensions Boot in Safe mode, and look in the folder /System/Library/Extensions for any third-party kernel extensions (files that end in .kext). Remove the kernel extensions and check for persistence of the issue.
Repair drive damage In the case of drive directory damage or problems with permissions, the solution is usually to use Apple's Disk Utility to repair the disk. Of course, you won't be able to perform this operation normally (simply launching the Disk Utility application, located in Applications/Utilities, and initiating a disk repair) if your system will not startup. So two options exist:
Insert your Mac OS X 10.4.x (Tiger) media (DVD or CD) and restart the computer while holding down the "C" key. Once the computer has booted from the installation disc, select "Utilities" from the menubar and open Disk Utility. Repair the disk, then quit Disk Utility and restart your system.
Alternatively, you can repair the disk while booted in single user mode if you do not have access to a retail Mac OS X 10.4.x (Tiger) DVD/CD. To startup in single user mode, hold down the "Command" and "S" keys simultaneously at startup. Once properly booted, type the command fsck at the prompt. Repeat these process until no errors appear.
Uninstall the update(s) An extreme measure is uninstallation of the most recently applied update(s).
This can be accomplished via the following process; adapted from our tutorial on reverting to a previous iteration of Mac OS X. Note, however, that reverting your system will remove any refinements brought by the update and leave your system open to potential vulnerabilities.
First, make a backup of your current Mac OS X installation with the Security Update applied, problematic as it may be. If there is an issue along the way, your valuable data will be safely intact in its current form.
Next, you'll need to perform an Archive and Install process to remove all of the Security Update's (and potentially problem-causing) components, and replace them with the components of a fresh copy provided by the Mac OS X disc that shipped with your system, or a retail Mac OS X disc. Unfortunately, this means you will lose some system settings and some or all third-party system add-ons.
To begin the process, insert your Mac OS X CD or DVD, as indicated above. Restart your machine and hold down the "C" key to boot from the newly inserted disc. Follow the on-screen instructions, and after accepting the license agreement, click "Options." Select "Archive and Install," and check the "Preserve User and Network Settings" option if you'd like to do so.
After the installation process is complete, you will be left with an earlier Mac OS X system that (hopefully) does not suffer from the problems generated by the Security Update. Use Software Update or Apple's download page to download the update that brings your system to a state directly prior to the Security Update
MacFixIt reader Paul Honis is among the many readers who found success with the aforementioned fixes. He writes:
"I installed today's three updates this evening and got an unresolved Kernel Panic on the restart. A second restart yielded the same result. I restarted in single-user mode, ran fsck which took longer than usual, unplugged all USB and FireWire devices including the keyboard and mouse and restart succeeded. Re-plugged the keyboard and mouse and after successful reboot I can now run iCal, Safari and Mail."
Feedback? [email protected]."
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