You may receive the following error message when carrying out a search from local, extranet or internet in SharePoint services 3.0
The Web application at http://[URL to SharePoint]/ could not be found. Verify that you have typed the URL correctly. If the URL should be serving existing content, the system administrator may need to add a new request URL mapping to the intended application.
Solution:

1.       Login in SharePoint server (WSS machine).

2.       Open the SharePoint central administration and select the OPERATION menu.

3.       Select Alternate access mappings menu  under Global configuration

4.       Click Add internal URL and then select SharePoint Site which is your needed site from within the alternate access mapping collection drop down menu.

5.       Type the full URL you require in the space provided. For example http://sharepoint.iotap.com.

6.       Select your required zone. For our example we select internet. Click save which should then take you back to the mapping list.

It should work 100% perfectly.

For more information about alternate access mappings visit http://technet.microsoft.com/en-us/library/cc288173.aspx