@ kop007
This goes beyond my experience, in that the things suggested have in the past resolved the continual restart request. So I feel there may be something else in the mix and it would probably be easier and quicker to do a reinstall, uninstall, reboot, install, reboot.
It would probably be best to download the latest version of avast and save it to your HDD, somewhere you can find it again. Use that when you reinstall.
@ BonnieM
I updated and registered and now it wants to continue restarting my system.
What is your OS, and why did you need to register ?
Try this link AAVM subsytem detected and RPC error.
http://www.avast.com/eng/faq-other-questions.html#idt_1539 this is usually accompanied by a Red circle over the avast icon ?
It can also be an indication that you have another AV installed or remnants of another AV.
Have (or did) you another AV installed in this system, if so what was it and how did you get rid of it ?
You to may be better to try the re-install if my previous suggestions to kop007 don't resolve the problem.