Windows no arranca -ndis.sys corrupto-

[YaInMuS]

Hola! después de instalar unas actualizaciones en mi netbook con Windows 7 (Ultimate) el PC no arranca, sucede lo siguiente al encenderlo:

Al cargar el logo de windows, se queda a medias y sale esto:

"Windows está cargando archivos"
"System recovery options"
"Startup Repair is checking your system for problems..."
Startup Repair cannot repair this computer automatically

Problem details:

Problem Event Name: StartupRepairOffline
Problem Signature 01: 6.1.7600.16385
Problem Signature 02: 6.1.7600.16385
Problem Signature 03: unknown
Problem Signature 04: 21200290
Problem Signature 05: AutoFailover
Problem Signature 06: 6
Problem Signature 07: CorruptFile
OS Version: 6.1.7600.2.0.0.256.1
çlocale ID: 1033

Diagnosis and repair details

[...]
test performed:
Name: system disc test
Result: completed successfully

test performed:
Name: disc failure diagnosis
Result: completed successfully

test performed:
Name: disc metadata test
Result: completed successfully

test performed:
Name: target OS test
Result: completed successfully

test performed:
Name: Volume content check
Result: completed successfully

test performed:
Name: Boot manager diagnosis
Result: completed successfully

test performed:
Name: system Boot log diagnosis
Result: completed successfully

test performed:
Name: Event log diagnosis
Result: completed successfully

test performed:
Name: Internal state check
Result: completed successfully

Root cause found:
Satartup Repair has tried several times but still cannot determine the cause of the problem

Session details
[...]

Root cause found
Boot critical file C:\windows\system32\drivers\ndis.sys is corrupt

Según lo que veo, es un archivo, el ndis.sys, el causante del error. El problema es que no puedo iniciar tampoco en Modo seguro, ni en Modo seguro con funciones de red, ni con simbolo del sistema, he intentado tambén restaurar sistema desde la opción del Startup Repair, también he probado la opcion de iniciar windows normalmente y con la ultima configuración que funcionó.

Nada funciona y me urge mucho areglarlo.

Alguna idea?

Muchas gracias!