Windows Vista SP1 - Missing acpi.sys file
Visits: 9146	Monday, April 28, 2008

Few days ago, the Vista SP1 was ready to download on Windows Update.
I preferred to use my notebook as tester, before install it on my central PC. The installation completed successfully, apart the time used for it (about 45 mins). I followed the upgrade step by step, I was near my notebook all the time, working on the other PC.

In the evening I decided to start the SP1 installation on my central PC, hoping all will be ok, but when I came back, I had bad surprise: PC blocked at 98% of installation (Step 3 of 3, if I remember correctly). I had to reset it, but it was impossible to start Vista because I got the acpi.sys missing file error.

With a Reset+F8, I started the last configuration, but the Vista SP1 installation started again. I hoped all will be ok this time and…. it was!

So I was thinking about it.. which is the difference between the first and second update?
Simple: I was in front of PC!
Yep.. during second installation I saw PC going on “energy safe mode” turning off my display, but always I was moving mouse to exit on that mode.

In this way, the installation completed successfully.

Hope it will be helpful.

Bye :)

this happened to me. how did you resolve the problem?

Written by Stephenie - Thursday, September 25, 2008 at 6:49 AM

this happened to me. how did you resolve the problem? I resolved moving mouse during installation, in this way for the PC was impossible to go into "safe mode". Pay attention: this solution was good for me, many other people has the same problem but they needed different solutions.. find your searching on the web.

Written by ZofM - Thursday, September 25, 2008 at 10:46 AM

well, i have the same problem and first my safe mode was aboutover 10 min i changed in 9999 min after that i manually tried to install and he is stuck at Step 1 of 3 98% and he is stuck ages..... and i tried to restart but got that acpi.sys error and i did system recovery and it rollback i treid this 3 times same freaking problem can someone help me ?

Written by Mesut - Friday, February 13, 2009 at 9:10 PM

Same problem with me. I have Vista Ultimate and tried to install Vista SP1. The installation got stuck at Step 1 of 3 98% and stuck there.... I tried to restart the Pc manually and that's when I got "ACPI.SYS" missing. Does not enter Safe Mode, not LKGC works. Looks like re-installation is the only way......?

Written by Mufeed - Thursday, February 26, 2009 at 4:17 PM

i have exactly the same problem as mufeed (i even have ultimate as he), ecept i am not sure if it was stuck at 98%. I just put my laptop on update during the night, when i woke up - it was trying to repair itself automaticly (doesnt work). I cant even press F8 - it goes to repair mode straight away. When i go see the details of problems - it says there are 2 main errors - file C:\windows\system32\drivers\ACPI.SYS is corrupted. Fixing method: fixing the file. error.error code 0xa fixing system. error.error code 0x2 checking and fixing system file integrity. error. error code 0xa Main problem was found: ------------------------ Important for loading file is corrupted: C:\acpi.sys ------------------------- First it tells u about acpi.sys in drivers, then in C:\ Hope someone would help me

Written by blackalegator - Thursday, May 21, 2009 at 8:47 AM

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