Hi! I am a new guy here and I already have a problem ;D. I have installed AVAST and when I start it a message appears: The parameter is incorrect. Unknown error 87.
Can anyone help me. Tnx

Did you reboot after installing?
When exactly do you get this message?
What version of Avast?
What OS?

Please see my post in this thread: http://forum.avast.com/index.php?board=2;action=display;threadid=8900

This is the same thing.

I have Win Xp Pro(service pack 2)
I restared my pc,started avast and then I got the message.
I have 4.5 Home version

So if you go to My Computer → Help → About Windows, what does it show, exactly? Can you post a screenshot of the About box?

As I said, I’m 99% sure that your SP2 version is not the official release one - build 2158.

Thanks
Vlk

Click on start
Click on run
Type “winver” in the box (without the quotes)
Tell us what version is reported.

something like this is what you should get:
Version 5.1 (build 2600.xpsp_sp2_rtm.040803-2158 : Service Pack 2)

Vlk…
Microsoft Windows version 5.1(Build 2600.xpsp_sp2_rc1.040311-2315:SP2, v.20)

You do not have the official release of SP2, please do as Vlk suggested and let us know if it solved the problem.

I will
tnx

If you need/want to download the entire SP2 installation, you can do it from HERE

so I have to update to official release build 2158?

Yes, update to the official release. What you have currently is as they call it a “Release Candidate”. You could consider it as if it is a Beta version.