익스플로러에서 호환성 체크하는데 개발자 도구(단축키 F12)가 활성화 되지 않을 경우 대처법입니다.

출처 : http://answers.microsoft.com/ko-kr/ie/forum/ie8-windows_other/ie8-%EB%8F%84%EA%B5%AC-%EA%B0%9C%EB%B0%9C%EC%9E%90/fca1ff1e-e522-4b6c-89a4-755a8fc1e545

메모장을 실행 후 아래 값을 복사 후 붙여넣기 한 다음 다른 이름으로 저장 ie.reg 로 저장한 다음 실행 하시면 됩니다. 

Windows Registry Editor Version 5.00 

[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\IEDevTools]
"Disabled"=dword:00000000 
"UseDevToolsDebugger"=dword:00000001
"Pinned"=dword:00000000 
"Minimized"=dword:00000000 
"MinimizedRestoreHeight"=dword:00000000
"MenuBar"=dword:00000001 
"ActiveTab"=dword:00000000 
"ActivePaneLeft"=dword:00000000 
"WindowPos"=hex:0a,00,00,00,0a,00,00,00,00,04,00,00,00,03,00,00
"1"=hex: 

[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\IEDevTools\Options]
"ValidateHtml"="http://go.microsoft.com/fwlink/?LinkID=129216&verbose=1&uri=%url%"
"ValidateCss"="http://go.microsoft.com/fwlink/?LinkId=129217&profile=css2&warning=2&uri=%url%"
"ValidateRss"="http://go.microsoft.com/fwlink/?LinkId=129220&url=%url%"
"ValidateLocalHtml"="http://go.microsoft.com/fwlink/?LinkId=129218"
"ValidateLocalCss"="http://go.microsoft.com/fwlink/?LinkId=129219"
"ValidateLinks"="http://go.microsoft.com/fwlink/?LinkId=129221&check=Check&hide_type=all&summary=on&uri=%url%"
"ValidateAcc508"="http://go.microsoft.com/fwlink/?LinkId=129222&rptmode=-1&url1=%url%"
"ValidateAccWCAG"="http://go.microsoft.com/fwlink/?LinkId=129223&rptmode=2&url1=%url%"
"ValidateHtmlDomain"="w3.org"
"ValidateCssDomain"="w3.org"
"ValidateRssDomain"="feedvalidator.org"
"ValidateLocalHtmlDomain"="w3.org"
"ValidateLocalCssDomain"="w3.org"
"ValidateLinksDomain"="w3.org"
"ValidateAcc508Domain"="contentquality.com"
"ValidateAccWCAGDomain"="contentquality.com"

[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\IEDevTools\Options\BkgColor]
"ClassIDBkgColor"="#FFCCCC"
"LinkPathBkgColor"="#FFCCCC"
"TabIndexBkgColor"="#FFCCCC"
"AccessibilityBkgColor"="#FFCCCC"
"ImgDimsBkgColor"="#FFCCCC"
"ImgSrcBkgColor"="#FFCCCC"
"ImgSizeBkgColor"="#FFCCCC"
"ImgAltTxtBkgColor"="#FFCCCC"

[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\IEDevTools\Options\DisableScript]

[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\IEDevTools\Options\Resize]

[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\IEDevTools\Options\Ruler]
"SnapToXY"=dword:00000001 
"SnapToElements"=dword:00000000 
"HideTicks"=dword:00000000 
"HideEndPoints"=dword:00000000 
"RulerCurrentColor"=dword:00000000
"RulerColor1"=dword:00ffffff 
"RulerColor2"=dword:00000000 
"RulerColor3"=dword:000000ff 
"RulerColor4"=dword:0000ff00 

[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\IEDevTools\Options\ZoneOptions]

[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\IEDevTools\ValidateConsent]