Rpcss error message at startup

Can someone please help me. I am new to Avast! and after installing version 4.7.844, I get an error message at startup that Rpcss has caused a critical error and will be shut down. I cannot clear this message and keep it off. It reappears each time I try to clear it. Once Avast is finished loading, I can clear the message and it doesn’t come back.
Is there a setting in Avast that can keep this from happening? Should I replace or reinstall Avast?
I am using windows 98.
Thank you for your help.
rdloper

Is there any other antivirus installed in your computer?
Did you install any in the past?

If you run the setup.exe file that you downloaded to install avast, won’t it show you an option to repair your installation?

Thank you for your response. Yes, I was running McAfee Internet Security Suite 2006 and it was killing me. It would slow down my startup and cause other problems because it seemed to take forever to update or scan. When I tried to uninstall it, I could not. So, when Avast installed, it removed it for me.
I have just run the repair and will check to see it this takes care of the problem.
Thank you again.

No… impossible.
avast NEVER removes other software in order to install. What you should have seen was a message telling you that McAfee was IN FACT installed and warning you to NOT install avast over it…
You need to clean your computer from McAfee.

I don’t think so :cry: