Microsoft is infalliable in their wisdom of proper software design. They know better than you how a program should be designed. At least that's the impression I get from the Windows Search tool. Yesterday, I spent at least an hour increasing my productivity by unsuccessfully attempting to find files that contained the string "email". I know there files were there because I happened upon one that contained it. Windows gave me no indication that there might be a reason why I was not finding the files I was looking for.
Apparently Microsoft improved the search feature by making it not look in all files when it says it's looking in "all files". It makes the descision for you that, unless it knows the files extension and type (.txt, .doc, etc), it won't search the file. That means any files you have created without an extension, or files that use non-Microsoft types (.sql, .cfg, .php, etc), it will ignore them without telling you. There are modifications that you can make to return Windows to it's expected, legacy behavior. The details are in KB Article 309173. But to save you time, I have created a registry script that will alter (fix) this setting for you. Windows XP Search Fix. Just download and run!