I'm having the same problem
I'm having the exact same problems with Awstats and my Apache log files. I can get the live web update to work when I change the file persmissions on access_log to 755 but then after a couple minutes, I suspect it's Apache, resets the permissions causing me to get the same error:
Setup ('/etc/awstats/awstats.system.conf' file, web server or permissions) may be wrong.
Check config file, permissions and AWStats documentation (in 'docs' directory).
My log files also have the same naming convention (access_log, access_log.1, etc..) and can't figure out how to get all of them to load at once either.
Mandrake Linux 10
Awstats 6.1 (build 1.751)