The design of Google pages (both web search and custom search) seem to have issues with Internet Explorer 8. See examples:
Google Web Search in IE 8
Perform a search on Google using Internet Explorer 8 (try "blog" or "hello") and you’ll only see the top 3 or 5 results on the search results page. Now change the text zoom and other search results will magically appear. This video captures the bug.
Google Custom Search and IE 8
Google Custom Search too has issues with IE 8. Perform a search on some site that uses Google Custom Search (example – //search.labnol.org/) and it will put IE in an infinite loop. The only option you have is to end the iexplore.exe process through the Windows Task Manager. Check the video.