vista won't boot

[uknownerror]

my sustem wont boot because I get the message

file:\windows\system32\drivers\msisadrv.sys
status:0xc000000f
info:windows failed to load because a critical sytsem driver is missing or corrupt

safe mode is the same and sfc states that windows resource..cannot execute it

booting from the vista disk and trying to repair it it says that I have something plugged and must restart but I don't have anything but monitor,mouse,keyboard

system restore doesn't work either

if anyone have seen my other post I fixed it by doing a clean reinstal but I do not want to have to do it again beacuse I have to much work saved to it now

tips...help...man...
last time was different but I wanted to be safe and not install any updates because I think that was what screwed something up last time.After the clean reinstall I've just insalled my invidia drivers,sound driver and two games(l4d,total war)it worked for a couple days then I shut down yesterday and rebooted this morning but this message came up

custom box

 

[Chappy]

Ouch...was it the same issue last time too?
Usually if the system cannot even boot Safe Mode, then a needed system file is too corrupt to allow the OS to load even the safe mode files.

What are the circumstances around this latest problem? Like was this after the machine went into hibernation, or after a recent WinUpdate? All the info you can provide will help, but I find in allot of cases where Safe Mode won't boot, the end result is best fixed with a clean reinstall.

This driver is in Vista to provide support for the Legacy ISA bridge, which is being phased out of future MS OS's. PS2 connected mice and keyboards use the ISA bridge and may be causing the problem if you use them. If a legacy device using the ISA bridge fails to load the referrence to the isapnp.sys in it's .inf file, this could be what is happening here. I have to do further research to see if thi could be fixed somehow.