I thought posting on this excellent site would be a good idea while desperately trying to fix my machine.
After running an Avast scan yesterday, I awoke to find that my machine wasn’t booting and I was receiving the error “C0000135 %hs is missing”. Windows 7 wont repair and all system restore points are gone, my Boot drive has also seemingly changed drive letters.
Any help will be highly appreciated.
Please print these instruction out so that you know what you are doing
[*]Download OTLPENet.exe to your desktop
[*]Download the attached scan.txt to a usb drive
[*]Ensure that you have a blank CD in the drive
[*]Double click OTLPENet.exe and this will then open imgburn to burn the file to CD
[*]Reboot your system using the boot CD you just created.
Note : If you do not know how to set your computer to boot from CD follow the steps here
[*]As the CD needs to detect your hardware and load the operating system, I would recommend a nice cup of tea whilst it loads 
[*]Your system should now display a Reatogo desktop.
Note : as you are running from CD it is not exactly speedy
[*]Double-click on the OTLPE icon.[*]Select the Windows folder of the infected drive if it asks for a location
[*]When asked “Do you wish to load the remote registry”, select Yes[*]When asked “Do you wish to load remote user profile(s) for scanning”, select Yes
[*]Ensure the box “Automatically Load All Remaining Users” is checked and press OK
[*]OTL should now start
[*]Drag and drop the scan.txt into the Custom scans and fixes box, or double click the scan box
[*]Press Run Scan to start the scan.
[*]When finished, the file will be saved in drive C:\OTL.txt
[*]Copy this file to your USB drive if you do not have internet connection on this system
[*]Right click the file and select send to : select the USB drive.
[*]Confirm that it has copied to the USB drive by selecting it
[*]You can backup any files that you wish from this OS
[*]Please post the contents of the C:\OTL.txt file in your reply.
Many thanks for your reply essexboy, I really appreciate it. I have ran the suggested scan and I attach the log.
The biggest problem I see is that the System Drive has somehow been changed to a G: drive and not the usual C: which has changed to ‘System Reserved’
I see that you have FSRT on the system have you used it at any stage ?
As you should be using the 64bit version
For x64 bit systems download Farbar Recovery Scan Tool x64 and save it to a flash drive.
Plug the flashdrive into the infected PC.
From OTLPE locate the flash drive
Douible click e:\frst64
[*]The tool will start to run.
http://i1224.photobucket.com/albums/ee362/Essexboy3/Farbar/FRST2.gif
[*]When the tool opens click Yes to disclaimer.
[*]Press Scan button.
[*]It will make a log (FRST.txt) on the flash drive. Please copy and paste it to your reply.
Thanks for your reply. I installed FRST earlier but I wasn’t able to interperet it very well.
Log attached
Reboot the computer
From the repair my system menu
Select Command prompt
http://i1224.photobucket.com/albums/ee362/Essexboy3/RepairVista_7277.jpg
At the command prompt type the following
Bootrec.exe /FixMbr
bootrec /FixBoot
exit
Once finished type Exit
Now retry a normal boot
It says “Operation completed successfully” but upon reboot the usual c0000135 BSOD error comes up. Not looking good is it?
This has the hallmarks of the TDL hidden partition although at the moment I cannot see it
However, the active partition is the correct one
Lets check something out though
Run the reatogo disc and then OTLPE
In the custom scans box type the following
/md5start
consrv.dll
/md5stop
HKLM\ControlSet001\Control\SessionManager\Subsystems /s
Press scan
Then attach the resultant log
I very much appreciate your continuing help. Log below:-
It looks like the subsystem control key has been wiped out
I can try to add it but there is no guarantee it will work though
Download the attached fix.txt and transfer to the sick computer
Run OTLP
Click the Run Fix button
A dialogue will open asking for the location of fix.txt
Navigate to the file, select it
Press run fix again
On completion retry normal windows
Same again 
As much as I really don’t want to, do you think it’s time to cut my loses and do a reinstall?
The stop: c0000135 error is generally caused due to error and bad clusters in the hard disk. From your post, I understand that a disk check has already been performed. Let’s run a disk check again and this time, let’s check for both file errors and physical errors, and select both Automatically fix file system errors and Scan for and attempt recovery of bad sectors.
information from a microsoft website
that what someone posted to someones post, do a disk check.
can you boot into safe mode?
To be honest that would be the quickest option
You can use OTLPE to remove to backup all the data you want to keep
OK, I think I will just take a backup and start from scratch.
Thank you very much for everyone’s comments and especially Essexboy, I appreciate the effort involved.
Just sorry we could not resolve it for you