
When you search for a specific string, using the built in search component - windows may not search unknown file types!
A really a simple registry hack will fix the problem.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\ContentIndex
FilterFilesWithUnknownExtensions=1
0 ignore file, 1 search them all
http://support.microsoft.com/default.aspx?scid=kb;en-us;309173