Event ID: 4, Source: Microsoft-Windows-Kernel-EventTracing, maximum file size for session "ReadyBoot" has been reached.

Hello,
I upgraded my machine to Win7 x64 Pro about 3 weeks ago. My HW is an Asus mobo, Intel Q9450 w/8GB RAM. The boot drives are two Raptors configured as RAID01. All the drivers are the latest available from Intel, Asus and 3rd party vendors. My WEI is 5.9, limited by the disk transfer rates, otherwise 7.1 and 7.2 on the other indexes.
I've been receiving these errors at boot;

Log Name:      Microsoft-Windows-Kernel-EventTracing/Admin
Source:        Microsoft-Windows-Kernel-EventTracing
Date:          11/10/2009 7:51:03 AM
Event ID:      4
Task Category: Logging
Level:         Warning
Keywords:      Session
User:          SYSTEM
Computer:      herbt-PC
Description:
The maximum file size for session "ReadyBoot" has been reached. As a result, events might be lost (not logged) to file "C:\Windows\Prefetch\ReadyBoot\ReadyBoot.etl". The maximum files size is currently set to 20971520 bytes.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="Microsoft-Windows-Kernel-EventTracing" Guid="{B675EC37-BDB6-4648-BC92-F3FDC74D3CA2}" />
    <EventID>4</EventID>
    <Version>0</Version>
    <Level>3</Level>
    <Task>1</Task>
    <Opcode>10</Opcode>
    <Keywords>0x8000000000000010</Keywords>
    <TimeCreated SystemTime="2009-11-10T12:51:03.393985600Z" />
    <EventRecordID>28</EventRecordID>
    <Correlation />
    <Execution ProcessID="4" ThreadID="164" />
    <Channel>Microsoft-Windows-Kernel-EventTracing/Admin</Channel>
    <Computer>herbt-PC</Computer>
    <Security UserID="S-1-5-18" />
  </System>
  <EventData>
    <Data Name="SessionName">ReadyBoot</Data>
    <Data Name="FileName">C:\Windows\Prefetch\ReadyBoot\ReadyBoot.etl</Data>
    <Data Name="ErrorCode">3221225864</Data>
    <Data Name="LoggingMode">0</Data>
    <Data Name="MaxFileSize">20971520</Data>
  </EventData>
</Event>

The image for PID 4 is listed as System.

My searches have turned up similar events listed but no solutions.
Any help would be appreciated.
Cheers!