Stop, don't go reinstalling yet, specially as the machine is still under warrenty..As soon as you do that, there goes your warrenty..Take it back to them if you can. Or follow below and use Vista Recovery Console
Vista’s System Recovery Console
First, Boot from your Vista installation CD.
Select your Vista Install from the list in “Windows Boot Manager”
· Microsoft Vista Setup (x86)
· Microsoft Vista Setup (x64)
Press enter.
You will then see “Windows is Loading Files”.
Next, the “Language Screen” will come up. Since you have already selected this option when you installed Vista, just click on “Next”.
Now you will see the “Vista Installation Screen”
DO NOT CHOOSE “Install Now”
Instead, towards the bottom left of the window you will see.
· “What to know before installing Windows”
· “Repair your Computer”
Choose and click on “Repair your Computer”
You will then come to the “System Recovery Options”. Choose “Microsoft Windows Vista” from the list. Then click “ Next”.
You will now have the option to choose which “Recovery Tools” you wish to use.
This list provides details to the five tools that can help you repair your Vista installation. These tools are:
1. “Startup Repair”
Automatically fix problems that are preventing Windows from starting:
Startup Repair is an automated repair process that scans your Vista installation for problems and attempts to automatically fix them. When you select to repair Vista from the Vista setup screen, and Vista detects problems, this process will be started automatically. You can cancel this process at any time to access the other repair tools described below. The Startup Repair process has already been introduced above when we discussed performing an automated repair.
2. “System Restore”
Restore Windows to an earlier point in time:
System Restore allows you to restore your computer's configuration, driver information, and programs to a previous state while leaving your existing data intact. Using this option can typically fix a installation's problem if it is not associated with faulty hardware. In order to use this option, you must have had System Restore enabled in Vista so that there are restore points available to restore to.
3. “Windows Complete PC Restore”
Restore your entire computer from a backup:
Complete PC Restore is a feature that allows you to restore your entire computing environment from a backup image that you created previously. The ability to create backup images for Complete PC Restore is only available in Windows Vista Business, Ultimate, and Enterprise. If you have tried all possible steps to repair your computer, and have a Complete PC Restore backup image available from when your computer was operating properly, then you can use this repair option to restore that image.
4. “Windows Memory Diagnostic Tool”
Check your computer for memory hardware errors:
Windows Vista comes with a diagnostic tool that allows you to check the memory installed in your computer for errors. This will allow you to determine if the actual memory (RAM) hardware installed in your computer is creating errors.
5. “Command Prompt”
Opens the Command Prompt window:
The Command Prompt repair tool allows you to open a command prompt that you can use to access the files and registry information on your computer. This is an invaluable tool for removing security threats such as worms, rootkits, and other malware from your computer and to be able to access files when Vista fails to boot up.
Chkdsk - Scan your hard disk for errors and fix them.
Choose the above options that best fits your computer problems.
The first option (Startup Repair) will run automatically. And will fix or repair Vista’s MBR and check for any corrupt files and folders.
NOTE: This option will also remove any installed program(s) that could be causing Vista not to start, or run correctly
