Hi,
In our new SPS 2010 environment we were trying to configure search. When we logged into the search service via central administration and clicked on content sources we got this error message "The search application 'Guid' on server ServerName did not finish loading. View the event logs on the affected server for more information." In the event viewer I was able to get this message:

Log Name:      Application
Source:        Microsoft-SharePoint Products-SharePoint Foundation
Date:          20-11-2011 01:45:35
Event ID:      6398
Task Category: Timer
Level:             Critical
Keywords:    
User:              NETWORK SERVICE
Computer:      rahul-HP
Description:    The Execute method of job definition Microsoft.Office.Server.Search.Administration.IndexingScheduleJobDefinition (Guid threw an exception. More information is included below.

The search application Guid on server ServerName did not finish loading. View the event logs on the affected server for more information.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="Microsoft-SharePoint Products-SharePoint Foundation" Guid=Guid />
    <EventID>6398</EventID>
    <Version>14</Version>
    <Level>1</Level>
    <Task>12</Task>
    <Opcode>0</Opcode>
    <Keywords>0x4000000000000000</Keywords>
    <TimeCreated SystemTime="2011-11-19T20:15:35.334377700Z" />
    <EventRecordID>48170</EventRecordID>
    <Correlation ActivityID="Guid" />
    <Execution ProcessID="2884" ThreadID="2996" />
    <Channel>Application</Channel>
    <Computer>rahul-HP</Computer>
    <Security UserID="S-1-5-20" />
  </System>
  <EventData>
    <Data Name="string0">Microsoft.Office.Server.Search.Administration.IndexingScheduleJobDefinition</Data>
    <Data Name="string1">Guid</Data>
    <Data Name="string2">The search application Guid on server ServerName did not finish loading. View the event logs on the affected server for more information.</Data>
  </EventData>
</Event>

So to come out of it I went to create a new search service instance. I went to Central Administration--> ManageServiceApplications --> new --> Search service Application.

A modal window opened as shown below:

Provide values and make sure that the account you are using as search service account must have at least read access to your web applications.

Now I was able to configure my content sources and get my items crawled.
I hope this will help you out.