Hostname: a352vg.avast.com
IP Address: 46.165.196.140
Hostname: a543he.avast.com
IP Address: 46.4.66.67
The IPs for you in Spain evidently are hosted in Germany. Below are the respective IPs resolved thru my ISP here in the USA. You may want to try them, but for me, I also get a blank page in Firefox when using the IPs. In Opera, I get an error page generated by Opera, not the web site. Same with your IPs. However, I can visit the named sites as they resolve thru the browsers, using the bookmarks that I've always used.
Hostname:
www.avast.comIP Address: 208.43.71.134
Hostname: files.avast.com
IP Address: 109.123.116.34
I thought that
http://208.43.71.134:80 would display the site, but it didn't.