After logging in, you are usually redirected to the root node of your site, in this case /1/2/. In your case editors no longer have access to this node, hence the error.
Hi
I think U can create new siteaccess ex. site4editor (copy admin siteacces)
and in site.ini change:
[SiteSettings]
IndexPage=/content/view/full/YOUR_NODE_ID/
DefaultPage=/content/view/full/YOUR_NODE_ID/
[DesignSettings]
SiteDesign=admin
and add
[SiteAccessSettings] AvailableSiteAccessList=site4editor