Which is your firewall?
Also, you could create a dump, download and run
http://public.avast.com/~vlk/hangrep.exe . In the list of processes select ashserv.exe (the one which is taking the resources) and use the Save button. This generates a file which you can either send to his email address vlk (at) avast.com (if it's smaller than e.g. 1 MB, ZIPed), or upload to
ftp://ftp.avast.com/incomingAlso, check the folder <avast>\data\log
Are there any files called unpXXXX there (where XXXX is a random number)?
If so, send them to vlk (at) avast.com
They may contain more information about the problem (maybe a link to this thread).