No results displayed while do a search in Office SharePoint Server 2007

When you search for file types or contents in Office SharePoint Server 2007 Search Center with tabs template or Search Server 2008 you do not see any results. You also do not see any errors on the results.aspx page and Event Viewer on the server.
When you enable verbose logging on the server and try the search again, we can find the below errors.

w3wp.exe (0x1454) 0x164C SharePoint Portal Server WebParts 8dxr Unexpected SearchBoxEx AfterDeserialize begin
w3wp.exe (0x1454) 0x164C SharePoint Portal Server WebParts 8dxt Unexpected SearchBoxEx AfterDeserialize end

Edit the results.aspx page and Check if the “Search Core Results” web part is present.
If no then the issue is resolved by adding the “Search Core Results” web part which is missing.
If you see the web part in the results.aspx page, then the issue is due to Invalid XML information is passed to the “Display Discovered Definition” feature.

What next ???

Click on Modify Shared Web Part and uncheck the “Display Discovered Definition” Feature.
Then Click on OK and publish the page
Now you should be able to get the search results.

Small description about “Display Discovered Definition” Feature which I could find online
The Definition Extraction feature finds definitions for candidate terms and identifies acronyms and their expansions by examining the grammatical structure of sentences that have been indexed (for example, NASA, radar, modem, and so on). It is only available for English. Definition extraction feature in MOSS 2007 is a feature that extracts meaning of definition from indexed text. User enters a search query “X”, search  returns from the document index a ranked list of sentences containing definitions of “X”, such as “X is Y” with links to the documents in which the definitions were found. In MOSS, implementation definitions are extracted from free text rather than from glossaries.
Definition Extraction feature is integrated with Search Feature at Crawl/Indexing and Query times. During the crawl, tokens with alternate definitions are added to search database. At query time passed search token is compared with existing entry in definitions database. If a match is found the definitions link is populated at the bottom of the search results page. Collapsing the link shows number of definitions.
It’s a default setting and cannot be customized. You can turn off Definition Extraction by Editing the Search Centre results page in question, modifying the Search Core Results web part, and turning off ‘Display Discovered Definition’.

Hope the above information is helpfull