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Windows 7 chkdsk bug linked to antivirus software

Hard disk

By Barry Collins

Posted on 30 Nov 2009 at 14:39

Antivirus firm Avira has admitted it's working on a fix for a mysterious Windows 7 bug that prompts the Check Disk utility to run at every start-up.

We reported earlier this month how the chkdsk bug refused to go away, having first reared its ugly head in the beta version of the operating system released earlier this year.

The glitch sees chkdsk report a potential error on the PC's hard disk, before reporting a clean bill of health once it's completed a scan. The only way to prevent the chkdsk screen running on start-up is to disable the utility.

Microsoft has remained mysteriously quiet about the issue, but several of the readers who commented on the PC Pro blogs and internet forums linked the bug to Avira antivirus software.

Now the company admits that it and other antivirus providers may have a problem. "As far as we can tell from the current state of investigation, the problem occurs in special conditions, when an operation is performed upon an already deleted file," Avira's technical editor, Dirk Knop, reports on the Avira TechBlog.

"This leads to the situation that the NTFS driver/the windows 7 kernel deems the file system as corrupted (which it is not) and sets the dirty-flag of the NTFS partition. This in turn leads to the chkdsk-run on the next start of the system. In previous versions of the windows kernel, the operating system just returned an error."

Avira adds that it should issue a hotfix for the problem this week, although it warns that "many other antivirus products seem to trigger this behaviour occasionally too, as we learned during the investigation of the problem".

Knop adds that Microsoft itself may be forced to address the issue with a Windows Update.

(Thanks to PC Pro reader Exlons for the tip-off.)

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User comments


I thought it my pc I was all set to reinstall software or even send the Hard disk back

I have just installed W7 and have avira. thank you for the heads up... looking forward to the piece on security

By milcome on 30 Nov 2009

Humble pie

PC Pro has been milking the chkdsk 'bug' for months. Now it turns out it's not a problem within Windows at all.

Well done for giving a reader credit.

By Stiggy on 30 Nov 2009

I see that it is still being referred to as a "Windows 7 bug" despite it being Avira that is making the fix in its own software. Hmm.

By halsteadk on 30 Nov 2009

@halsteadk: you should know by now that generating hits is more important for a title than actual accuracy.

Knop: "Microsoft itself may be forced to address the issue [that was generated by our 3rd party software."

By phantombudgie on 1 Dec 2009

Seems to me some people are attributing blame without understanding the precise cause. (Which I don't, either)

The fact that Avira is making a fix doesn't necessarily mean it's Avira's fault. As an application programmer, I would frequently make a fix in my system to deal with issues in another, rather than wait for the other to deal with it. It's just customer service.

Avira are suggesting other companies have the issue as well - which matches (by memory) discussions on PCPro. While that suggests the issue is a Windows issue after all, that doesn't means it's a Windows BUG - it could be various AV companies have exploited or expected an undocumented "feature" that now has changed. And as an undocumented feature, well, that's the risk you take. So, right now, seems to me "case not proven" either way.

By AdrianB on 1 Dec 2009

just antivirus?

I run Norton and have the same chkdsk/fsutil problem. Seatools says my disk is fine. I doubt this is just an antivirus software issue.

By mark_norman on 2 Dec 2009


I suffer the same problem with AVG. Annoying!!

By mikem2te on 3 Dec 2009


I am using Trend Micro Internet Security Pro and have the same problem.

I think it is definitely a Windows 7 problem as are many other quirks I am suffering from since acquiring a brand new computer with Windows 7 Ultimate installed!

By Borton1 on 3 Dec 2009

Timely read

glad I read this old newsletter as I was going to upgrade to W7 as soon as i could justify the total cost,think I will wait until this is fixed.

By phat_boab_6 on 10 Dec 2009

same using Nod32/64

just read this after having the chkdisk thing happen twice on HP dv9341 laptop running brand new Win 7 downloaded from Digital River and ESET/Nod32 previously impeccably...hmmm Microsoft whats going on???

By willyw97uk on 28 Dec 2009

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