Hi Truong, I got the very same problem upgrading from Elgg 1.7.1 to 1.7.3, the dashboard and profile widgets showed the full site in each.

After much searching and fiddling, it turned out to be my mistake. Just use the htaccess file supplied with 1.7.3 to replace your current one and the problem disappears completely. You just need to rename your old file then rename the new one with the old one's name.

Note: if - like me - your Elgg site is a sub-directory within your domain, read inside the file for instrcutions on where to place the necessary setting. Good luck.

HI people,

Okay thanks fot all the extra input. I was just upgrading again to 1.7.3. and it all occured again... I'm going to try the .htaccess proposed thing. It seems like something about that, because I get blank pages all over the place when I navigate towards e.g. administrator panel. 

However when I click the complete mysite.com/pg/admin/statistics I get the full view again ...

I'll post the progress on the matter here.

Well people,

It's fixed! The site got hacked, so my index.php in the root and htaccess were totally messed up. I restored from backup en placed the new 1.7.4 core on the installation again. And placed some restriction in siteaccess plugin.

The site within site widget problem is like Bassam mentioned, use the htaccess_dist from the 1.7.4 version. Place any url-domain rewrites in here.

Well it has been fun :p till next time ;)