Try tapping F8 at startup, and from the list of startup selections, select Safe Mode by using UP Arrow Key to go there > then hit Enter.
Try a System Restore once there, to pick a Restore Point before your problem..
Click Start > Programs > Accessories > System Tools > System Restore > pick a different time > Next > etc
If Restore does not work and you do not have a Microsoft Vista DVD, make a Bootable Repair Disk to do a Startup Repair:
Download the ISO file at the supplied link, and make a Bootable Startup Repair Disk from it.
Go into your Bios/Setup, or Boot Menu, at startup, and change the Boot Order to make the DVD/CD drive 1st in the Boot Order, then reboot with the disk in the Drive.
At startup/power on you should see at the bottom of the screen either F2 or DELETE, to go into Bios/Setup, or F12 for the Boot Menu.
When you have changed that, insert that Bootable Disk you have made in the Drive, and reboot.
Above link shows what the process looks like, and a how-to, as it loads to the Repair Options.
Neosmart contains the contents of the Windows Vista DVD's "recovery center," as we've come to refer to it. It cannot be used to install or reinstall Windows Vista, and just serves as a Windows PE interface to recovering your PC. Technically, one could re-create this installation media with freely-downloadable media from Microsoft (namely the Microsoft WAIK kit, a multi-gigabyte download); but it's damn-decent of Microsoft to make this available to Windows' users who might not be capable of creating such a thing on their own.
Read all info at the website about creating and using it:
It makes a very good Vista Startup Repair Disk.
You can do a Startup Repair, System Restore, etc from it.
It is NOT a reinstall disk.
And the 32bit is what comes normally on a computer, unless 64bits requested.
1. Slave your Hard Drive in another computer, and read/save your Data from there.
2. Put your Hard drive in a USB Hard Drive Enclosure, plug into another computer, and read/save from there.
3. Or, use Knoppix Live CD to recover your Data:
Download/Save the above Knoppix Live CD ISO file.
Download the Vista Burning software from the above link.
After installing above ISO burning software, right-click on Knoppix ISO file > Copy Image to CD.
Knoppix does not install on your PC; just uses your PC's resources, RAM, Graphics, etc.
Change the Boot Order in YOUR computer/laptop to make the CD/DVD Drive 1<sup>st</sup> in the Boot Order.
Plug in a Flash Drive/Memory Stick, BOOT with the Live CD, and you should be able to read your Hard Drive.
When the desktop loads, you will see at least two hard drive icons on the desktop (one for your hard drive and one for the USB drive).
Click on the hard drive icons to open them up and figure out which drive is which.
Right-click the USB drive icon and choose "Actions > Change read/write mode" so you can write to the drive (it's read-only by default for security reasons).
Now find the files you want to back up and drag and drop them to the USB drive. When you are finished, shut down the system and remove the USB drive.
Dell Recovery options:
Above is Dell's way to reinstall Vista from the DVD to your computer.
And this way if you have a Recovery partition on your Hard drive.