After importing new EPG data via BigScreen EPG - the inbuilt EPG 'search' function in Windows 7 Media Center may not always work as expected - and may not return any valid results for keyword (and other) searches.
 
This problem is generally caused by the internal 'Windows Search Index' being out of synch with the new EPG data that's been loaded in (keeping in mind that all the searching functionality in Media Center is actually provided via the same Windows Search Components used by your Desktop search).

While this search index (provided by Windows Search) will most likely 'eventually' update itself after importing EPG data - there can be a long delay before this happens (up to 24-48 hours depending on the size of the EPG data being loaded) - and subsequent EPG imports inside that timeframe may invalidate the indexing that was done on previous data.

A known workaround (or hack) to this help with this problem is to force a "reindex" of the Media Center EPG data manually by calling the appropriate task.  To do this please type the following from a Windows Command Prompt (preferably run 'As Administrator'):-

%SystemRoot%\ehome\ehPrivJob.exe /DoReindexSearchRoot

After calling this function - your search index will start to be rebuilt (in the background) - so please allow some time for it to complete before attempting to use search (ie. it will not complete immediately and may take 5-30 minutes depending on the amount of EPG data loaded).

For more advanced windows users - this above 'reindexing' process may also be scheduled to run after each Big Screen EPG import. The simplest way to do this is to modify the existing Big Screen EPG Scheduled Task (if configured)- and add an action that runs directly after the epg processing (where bsetool.exe is called). 

The Big Screen EPG Help file provides some information on how to modify (and create) these scheduled tasks - please see the topic :

Scheduling Big Screen EPG to run by itself via 'Task Manager' >> Adding Additional Download/Script Actions to your Scheduled Task.