The same thing happened to me.
After working fine for months after a clean install of Vista my Vaio laptop suddenly refused to start.
Both Windows and Norton (NIS2009) would occasionally auto update but I'm not sure whether this preceded the crash or not. On boot up it displayed:
Windows Boot Manager
Windows failed to start. A recent hardware or software change might be the cause. To fix the problem:
1. Insert your Windows installation disk and restart your computer.
2. chose your language settings, and click "Next."
3. Click "Repair your computer."
If you do not have this disk, contact your system administrator or computer manufacturer for assistance.
File: \Windows\system32\drivers\NIS\1002000.007\SYMEFA.SYS
Status: 0xc0000098
Info: Windows failed to load because a critical system driver is missing, or corrupt.
I managed to use the Vista disk to get back to a previous restore point and all was OK for a week. Then it happened again. Same message, but this time the System Restore wouldn't work. All reboots resulted in the message above.
I've now spent two days re-installing Windows and all my apps and data but have held off putting NIS back on as I can't risk going through all that again.
Is there a solution to this or should I buy McAffee ?