I installed Avast free Anti virus today in Windows XP. I had Quick heal already in my system but it was not the latest version.

When the Smart scan began PC went into restart loop. After that I could boot into Windows once without restart. Though Windows didn't run at that time. So I restarted it again. Again the restart loop began. Now I have shut down the machine.

I tried to boot into safe mode but it's not possible. I don't understand the possible reason behind it. Could it be due to multiboot system?

Is there any solution to this issue so I can uninstall both the AVs safely and use Windows again without restart loop?

Also in this condition how much safe are the other OS installed on the device?

Can this issue affect other installed OS as well?


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    Elaborate when you say "It's not possible" to boot into safe mode. – Cheesus Crust Oct 31 '17 at 14:09
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    Why are you doing exactly what every security software vendors tells you NOT to do have multiple AV programs installed. Stop using multiple AV programs. Your current situation will not have to be solved be you reinstalling Windows. – Ramhound Oct 31 '17 at 14:16
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    @CheesusCrust I see GRUB. Advanced modes options are not visible. – mohinip Oct 31 '17 at 14:43

Two antiviruses on the same PC (more precisely: on the same OS installation) can bring real troubles: all antiviruses use the same techniques for malware detection (e.g. file tracking, interception of system calls, stacktrace analyzing, etc). So activity of the one of the antiviruses can be considered as intrusion actions by another antivirus. You should uninstall one of them anyway.

I tried to boot into safe mode but it's not possible. I don't understand the possible reason behind it.

I haven't reproduced your situation (I just haven't Windows box). But most of the modern antiviruses start functioning at the very beginning of OS boot process (this is intended for fighting some kind of sophisticated viruses). Perhaps, this is why you can not boot into safe mode.

Could it be due to multiboot system?

No. BTW what bootloader is on your PC? Is it grub or something else?

I suggest you to boot from LiveCD (or enter to bootloader menu, for example, in case of grub just hold Shift at boot time). Then you can uninstall on of the antiviruses. For example, you can try to remove the antivirus' directory from Program Files folder. Yes, it's dirty uninstallation. But it will stop antivirus. Please look at the documentation of antivirus vendor for details (probably, there is official uninstallation tool...).

IMPORTANT! Don't delete any files permanently. E.g. load from LiveCD, plug in an USB flash drive. Then, for example, do not just delete antivirus directory from Program files but move corresponding directory to flash drive. If something will go even worse (for example, Windows will not boot at all) you can easily restore the files. So you will able to try another approach.

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    Yes, it is GRUB. What to do if LiveCD is not there? I thought to try to remove AV from Ubuntu. But it might worsen the situation. – mohinip Oct 31 '17 at 14:45
  • You can not delete but move antivirus files to flash drive. If something will go wrong you can restore them. – flaz14 Oct 31 '17 at 16:29
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    So is it safe (for Ubuntu) to move the AV files from Ubuntu to flash drive? – mohinip Oct 31 '17 at 16:44
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    I mean that you can boot Ubuntu, them move antivirus files to removable drive, then boot Windows. If something will go wrong you can boot Ubuntu again and restore the files. – flaz14 Oct 31 '17 at 19:18

The issue of restart loop is resolved.

The steps worked for me:

  1. I chose Windows XP from GRUB menu.
  2. Then pressed and held F8 long pressing it. And options for safe mode appeared.
  3. Booted into 'safe mode with networking'.
  4. Connecting to internet, downloaded Uninstall utility for Quickheal AV and uninstalled it. (I had faced issues with connecting to the internet. I turned off Firewall and unchecked AV from network connection properties. Then I could connect to the internet.)
  5. Then restarted the Windows normally. Restart loop stopped and present AV is working fine.

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