Yesterday I’ve posted a trick on how to obtain Kaspersky Internet Security 2009 license key for free and I believe many has successfully got the key. From the comments on the article and forum, I found out that many people is unable to install Kaspersky Internet Security 2009 due to an incompatible software that is installed on the computer, specifically AVG 8. The error windows shows a message “Attention! Some incompatible software is installed on your computer. These applications cannot be used together with Kaspersky Internet Security 2009. In order to proceed with the installation, remove these applications.”

Selecting the incompatible software from the list and clicking the Remove button will launch Add or Remove Programs. Then another error “In order to proceed with the installation, please remove incompatible software (it is recommended to reboot your computer after uninstallation). Then run the installation again” The weird part was, AVG 8 has already been uninstalled on my test system!
After investigating the Windows registry, I found cause of the problem (registry keys) that is causing AVG incompatible software problem during Kaspersky installation.
I noticed that the Next button is blurred or grayed out. So I thought maybe I can use TurnItOn or DM2 to enable and access the restricted Next button. Tried but it doesn’t work.
The method that Kaspersky suggested on how to skip scan for incompatible Software when installing Kaspersky Anti-Virus 2009 or Kaspersky Internet Security 2009 is at this link. This way of fixing the problem can be somehow confusing for computer beginners because it involves folder options setting, going to a hidden All Users application data folder, open up command prompt and launch the setup.exe via command line switch.
I think the fix that I found myself would be much easier. Just launch Windows registry and navigate to the keys involved, back it up and then delete it. Here it goes.
1. Go to Start > Run.
2. Type regedit and click OK.
3. Navigate to this following registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\

right click the key, select Export and save it on your computer. Then delete AVG key. Try installing Kaspersky (kis8.0.0.357.exe) again. If it still doesn’t work, then run regedit again, navigate to:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\

right click the key, select Export and save it on your computer. Then delete AVG8Uninstall key. You should be able to install Kaspersky Internet Security 2009 now without getting the incompatible software prompt. This is fix is only if AVG is listed in the incompatible software window. If you have Norton, you can look for Norton/Symantec registry key at the same location above and delete it.
This option is recommended ONLY if you are absolutely sure that the third-party software was deleted but is still detected by the Setup Wizard of Kaspersky Internet Security version 2009. Otherwise after the program installation the operating system may malfunction and even crash.
For a list of incompatible software with Kaspersky Internet Security 2009, you can visit this page.
I actually had this problem when I was installing KIS 2009 on my test system but was somehow able to install KIS 2009 over it even if I got the incompatible software message. I can’t really remember how but I got through it. But if you’re unable to, you can use the solution above. Enjoy Kaspersky Internet Security 2009!