Trouble with 10.6.8 Update - blue scream, does not start the OS when it turns on. Should I stay with the old 10.6.7?

Question

The Disk Utility could not repair the disk neither the repairing installation of the OS X allowed me to start the OS, the blue frozen scream was still appearing. The HD erasing with the Disk Utility was the only choice, than installing the 10.6.7 OS.

Answer 1

I'm not entirely certain of what you've tried here, so some of this may be what you've already tried.
Get an external backup or two, made via the bootable DVD.  Recoveries and repairs sometimes fail, and data loss can result.
if Disk Utility is not repairing the disk structures, then you can try an add-on repair tool (which wouldn't be my choice, but some folks try that), or you can create an external backup and reinstall from distribution.  Attempting installation on a corrupt (or potentially failing) disk won't usually have desirable results.
After creating the external backup (or two), you can either replace the disk and reinstall, or can attempt to wipe and reinstall with the existing disk using the bootable DVD that came with your system (or a new Snow Leopard DVD from Apple) and particularly the Disk Utility tool that's available via the DVD Utilities menu, and migrate in your old data from the external backup.    I'd then download and apply the 10.6.8 Combo Update from Apple; and not the delta update from 10.6.7 (if that's what your Mac DVD has).
The data migration is part of the installation, and will attempt to bring in your existing files and your old environment, passwords and the rest of the settings from the external disk image.  (Assuming it's not corrupted.)
If you have reinstalled and have redownloaded and reloaded the combo update, then you likely have some sort of a hardware problem with your MacBook Pro; check with the local Apple Store for repairs, or whoever else you might be using for that.   Or replacement, of course.
I'm going to assume that you're using the OS X 10.6 client software that arrived with that MacBook Pro and have not installed and are not running the server version of OS X Server 10.6 (this forum);  the initial recovery sequence for this case is basically the same for either, though getting the various services back online after a disk corruption can be more involved.  You will need to use the 10.6.8 Server combo update here, though.