Can you paste your episerver.config <sites> section and EPiServerFramework <siteHostMappings> section.

<site description="Live Site" siteId="XXX">
      <siteSettings enableScheduler="true" stringCompressionThreshold="0"
        stringDelayedLoadThreshold="0" remoteWebServiceCulture="0" indexingDelayAfterPublish="00:00:20"
        uiDefaultPanelTab="0" indexingTextRegExp="[\p{N}\p{L}]{1}[\p{N}\p{L}-\._]*[\p{N}\p{L}]{1}"
        logServiceUrl="soap.tcp://localhost/TimeSpanAnalyzerView" uiImageTransparencyReplacement="White"
        globalErrorHandling="Off" uiSafeHtmlTags="b,i,u,br" uiOptimizeTreeForSpeed="false"
        sgmlParserDecodeCharEntities="false" disableVersionDeletion="false"
        remoteCacheListenerShortNames="" httpCacheVaryByCustom="path"
        httpCacheVaryByParams="id,epslanguage" httpCacheExpiration="00:00:00"
        httpCacheability="Public" pageCacheSlidingExpiration="12:00:00"
        remotePageCacheSlidingExpiration="02:00:00" uiEditorCssPaths=""
        uiEditorColors="" uiEditorHeight="250" uiEditorWidth="500" uiEditorValueOptions="0"
        urlRewriteExtension="" urlRebaseKind="ToRootRelative" pageUseBrowserLanguagePreferences="false"
        uiShowGlobalizationUserInterface="true" subscriptionHandler="EPiServer.Personalization.SubscriptionMail,EPiServer"
        globalErrorMail="xxx@xxx.com" mirroringRetries="5"
        mirroringRetryDelay="00:00:01" mirroringHtmlTextEncoding="Unicode"
        mirroringFileWriteRetryDelay="00:00:05" pageRootId="1" pageStartId="3"
        pageWastebasketId="2" pageOfficeStartId="0" uiMaxVersions="0"
        uiVersionMerging="true" pageValidateTemplate="false" uiKeepUserLoggedOn="true"
        siteUrl="http://staging.xxx.co.uk/" uiUrl="~/XXXCMS/CMS/"
        utilUrl="~/util/" siteDisplayName="xxx" errorMailHandler="~/util/SendErrorReport.aspx"
        pageFolderVirtualPathProvider="SitePageFiles" uiTheme="" enableEvents="true"
        enableRemoteEvents="true" operationCompatibility="None" mirroringSource="mirroringSourceEndpoint" />
    </site>
    <site siteId="Russia">
      <siteSettings enableScheduler="true" stringCompressionThreshold="0"
        stringDelayedLoadThreshold="0" remoteWebServiceCulture="0" indexingDelayAfterPublish="00:00:20"
        uiDefaultPanelTab="0" indexingTextRegExp="[\p{N}\p{L}]{1}[\p{N}\p{L}-\._]*[\p{N}\p{L}]{1}"
        logServiceUrl="soap.tcp://localhost/TimeSpanAnalyzerView" uiImageTransparencyReplacement="White"
        globalErrorHandling="Off" uiSafeHtmlTags="b,i,u,br" uiOptimizeTreeForSpeed="false"
        sgmlParserDecodeCharEntities="false" disableVersionDeletion="false"
        remoteCacheListenerShortNames="" httpCacheVaryByCustom="path"
        httpCacheVaryByParams="id,epslanguage" httpCacheExpiration="00:00:00"
        httpCacheability="Public" pageCacheSlidingExpiration="12:00:00"
        remotePageCacheSlidingExpiration="02:00:00" uiEditorCssPaths=""
        uiEditorColors="" uiEditorHeight="250" uiEditorWidth="500" uiEditorValueOptions="0"
        urlRewriteExtension="" urlRebaseKind="ToRootRelative" pageUseBrowserLanguagePreferences="false"
        uiShowGlobalizationUserInterface="true" subscriptionHandler="EPiServer.Personalization.SubscriptionMail,EPiServer"
        globalErrorMail="xxx@xxx.com" mirroringRetries="5"
        mirroringRetryDelay="00:00:01" mirroringHtmlTextEncoding="Unicode"
        mirroringFileWriteRetryDelay="00:00:05" pageRootId="1" pageStartId="3"
        pageWastebasketId="2" pageOfficeStartId="0" uiMaxVersions="0"
        uiVersionMerging="true" pageValidateTemplate="false" uiKeepUserLoggedOn="true"
        siteUrl="http://staging.yyy.ru/" uiUrl="~/XXXCMS/CMS/"
        utilUrl="~/util/" siteDisplayName="xxx" errorMailHandler="~/util/SendErrorReport.aspx"
        pageFolderVirtualPathProvider="SitePageFiles" uiTheme="" enableEvents="true"
        enableRemoteEvents="true" operationCompatibility="None" mirroringSource="mirroringSourceEndpoint" />
    </site>
  </sites>

<siteHostMapping>
    <siteHosts siteId="xxx">
      <clear />
      <add name="*" />
      <add name="staging.xxx.com" language="en" />
      <add name="staging.xxx.co.uk" language="en-GB" />
      <add name="staging.xxx.de" language="de" />
      <add name="staging.xxx.dk" language="da" />
      <add name="staging.xxx.no" language="no" />
      <add name="staging.xxx.pt" language="pt" />
      <add name="staging.xxx.nl" language="nl" />
    </siteHosts>
    <siteHosts siteId="Russia">
      <clear />
      <add name="staging.yyy.ru" language="ru-RU" />
    </siteHosts>
  </siteHostMapping>

Hi. You have the same pageStartId for both sites which EPiServer is not designed to cope with. Each site should map to a different branch in the page tree.

Thanks Paul.

Our sites all use a single tree with translations for each page. So this architecture would not work for us? 

Could the the 404 images be a result of a license warning? Try browsing directly to one.

Is there a reason you cannot use SSL on the existing site?

/Steve

There is no license warning - it's an enterprise license. 

The SSL issue is that a new domain/country would need to be added to the existing instance, which would result in considerable (up to 24 hrs?) downtime for the rest of the sites running on that IIS instance.