How can I remove a forkbomb from the Startup folder?
How to remove a forkbomb from the Startup folder?
Start your PC in "Safe Mode" (Startup programs do not run in safe mode, and only the basic drivers needed to start Windows are installed).
Then you can delete the offending batch file.
How To Start Windows Vista in Safe Mode
To begin entering Windows Vista Safe Mode, turn on or restart your PC.
You will see the Splash Screen
Before the Windows Vista splash screen appears, press F8 to enter "Advanced Boot Options"
Select "Safe Mode" and press Enter
Screenshots:
Source How To Start Windows Vista in Safe Mode
You can skip loading the contents of the Startup folder by holding down Shift as the computer starts and logs in. (Note that this doesn't work for startup applications loaded from the Registry or other locations, only the actual Startup folder.)
Try booting your laptop in Safe Mode by pressing F8 during the bootup sequence, from there, just locate the file in your Startup folder and delete it.
If you're worried about accidentally opening it, or something similar, you can boot up in Safe Mode with Command Prompt (Provided you can use Command Prompt), and delete it that way, instead.
Even safer than that would be to take the hard drive out and connect it to a machine that cannot open a batch file, thus unable to reactivate the sequence, and remove it that way.
If that's unavailable, you could always try and re-image the drive.