This is a documented XP problem.
Windows? XP has a known issue for not finding a number of File Types when you do a Search for Files "containing text" or using the "A word or phrase in the file" option. This can be remedied for many file types, but not all. The cause is the lack of a PersistentHandler value in the Registry for this type of file.
You can correct this by clicking Start, Run and entering REGEDIT Navigate to HKEY_CLASSES_ROOT and locating the entry for the file type in question. For example, .txt, .adm, .asp. Expand the branch for that file type, and if the PersistentHandler subkey does not exist, create it. Do this by clicking on the file extension key and going to Edit, New, Key. Name the Key, PersistentHandler. Click on the PersistentHandler sub-key. In Regedit's right pane, double click on the Default value and enter the following (copy and paste may be your best bet):
{5e941d80-bf96-11cd-b579-08002b30bfeb}
If the PersistentHandler sub-key does exist, do not change the default value. This could have very undesired consequences.
Close Regedit and reboot the computer. This file type will now be searched for "A word or phrase in the file" type searches.
An alternative is to download a small VB Script utility here. Save the file you just downloaded to your hard disk. Locate the file you just saved and double click it. Enter the file extension you wish to modify. If the PersistentHandler sub-key exists, no changes will be made. If it does not exist for the file type in question, the Registry will be updated accordingly. Reboot when you're finished with the file types you wish to change.
