A brace of "fatal errors" is hampering Windows 7-based computers that have been updated with Microsoft's first service pack for its current operating system.

In fact, since Windows 7 SP1 was released late last month, many users have been grumbling on forums about problems with the install of the update package.

Similarly, The Register has heard from lots of disgruntled readers who are wasting precious time having to rebuild their machines after the service pack had led to fatal flaws in the OS.

"Basically, if you have an OEM machine connected to a server running WSUS [Windows Server Update Services] with the default settings it offers and installs SP1 automatically. This is killing machines and stopping them booting with a C00000034 fatal error," said Reg reader Simon, who has seen 15 machines downed by the flaw.

"Best thing is, SP1 deletes restore points prior to installing!!!!"

Separately, Windows 7 punters applying the SP1 update package have stumbled into a reboot looping glitch after encountering: "Error C000009A applying update operation 120782 of 367890".

More about that particular bug can be found here and here.

Despite all that, Microsoft hasn't been forthcoming with us about what has gone wrong. And it looks like we've just found out why El Reg has been given the stone-cold silent treatment...

In the vendor's TechNet forums, one MS employee confessed today that the firm had yet to nail the cause of the errors.

"We're hard at work here trying to see what's happening on these particular failures," wrote a Redmond wonk with the handle Joscon.

"I don't have an answer yet, but as soon as I know something, you'll know it. Please keep me informed on any failures and symptoms you have on these machines."

The company is also pointing its customers at this knowledge base, which offers a work around to fix the "C00000034" cockup.

"And if you have logs/VHDs or an image of a machine with this problem, let me know through the blog. I'd like to get in-state failures so we can work on them but so far they have been few and far between," said Joscon.

But with Microsoft unable to pinpoint the exact cause, users are suggesting the only way to avoid the problem is to switch off WSUS. �

Error C000009A applying update operation 119595 of 334565 (\Registry\...) when loading SP1

Windows 7 Service Pack 1
for the problem issues scroll to bottom.

Your computer may freeze or restart to a black screen that has a "0xc0000034" error message after you install Windows 7 Service Pack 1 or a Windows Vista service pack

Error 0xC0000034 during Service Pack 1 installations for Windows 7 and Windows 2008 R2

Windows 7 customers hit by service pack 1 install 'fatal error' flaws
blog with some possible fixes listed

I have not done the SP1 for 7 yet was waiting just for this kind of info. Again those that had no problems are lucky.
Image those drives before you attempt to install any service pack! The fact that you are left with no restore points is not good.

I was waiting until I have all my tax info organized and on a flash drive for the accountant. Please let those of us who are less technically savvy know when the issues are resolved and this might be safer to install - I see there are three more monthly updates available today, I'll wait a few days on those too.

I generally follow Susan Bradley's lead and in her articles in the paid version of Window's Secrets newsletter she is still advising on holding off on sp1, when she gives the go ahead that is when I will give it a go.
I pay $5 for that newsletter and to me it really is worth it for the amount of info they provide, it is set up that you can make any monetary yearly payment to get it.

This was her advice in the last issue

"Still holding on Windows 7 Service Pack 1

This week, Windows 7 Service Pack 1 (KB 976932
) will show up in Microsoft's corporate patching tool, Windows Server Update Services.

As mentioned in my March 3 Best Practices column
, I'm still unwilling to give anyone including network administrators the green light to install SP1.

â–º What to do: I recommend that network administrators wait a while longer before putting SP1 on their networks."

she also provided a list of all the patches she cautions about in a patch watch post list which can be seen here at the lounge forum
Patch Watch adds problem-patch update chart

Witz

from her article Quote:
"Microsoft released two patches to fix problems with Windows 7's infamous first service pack. Both should be installed before updating to Win7 SP1.

KB 2533552 corrects a flaw that produces a failed SP1 update, leaving users with a cryptic error code (shown in Figure 1) and a difficult recovery. Systems that received SP1 through Windows Software Update Services were hit particularly hard, as noted in a TechNet blog.

KB 2534366 fixes an issue with multiple language packs; some systems would hang at a black screen after SP1 was installed.
If you haven't already successfully installed Windows 7 SP1, install both KB 2534366 and KB 2533552 first. And if Win7 SP1 is already installed, accept KB 2533552 for future service packs.

Yes, it's true; I'm finally ready to give the all-clear for Windows 7 SP1 but only after you've accepted KB 2533552 and KB 2534366, as noted above. Rather than using Windows Update, I urge you to download and install the SP1 update manually to make sure it's successfully added."

and the latest list of her recommendations for windows patches list
Regularly updated problem-patch chart
and the link to sp1 direct download
SP1

she mentions to allocate about an hour for this.