I have recently moved to a 64-bit Windows Server 2008 R2. I setup my Scheduled Tasks to run under one user (TaskUser) specifically created for the scheduler and most run just fine. However some of them do not run under TaskUser but will for my own credentials.

Here is the Event Log entry I found, which from my research points me to believe that it doesn't have permissions, but it does. It also has the option "Run with highest privileges" checked on. I have seen this particular checkbox work wonders on some tasks, but I have a number of them that it's not helping for.

The error is ERROR_ELEVATION_REQUIRED but the user is a member of the administrators group and has folder/file permission and is set to "Run with highest privileges"

Log Name:      Microsoft-Windows-UAC/Operational
Source:        Microsoft-Windows-UAC
Date:          4/27/2010 2:21:44 PM
Event ID:      1
Task Category: (1)
Level:        Error
Keywords:      
User:          LIVE\TaskUser
Computer:      www2
Description:
The process failed to handle ERROR_ELEVATION_REQUIRED during the creation of a child process.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="Microsoft-Windows-UAC" Guid="{E7558269-3FA5-46ED-9F4D-3C6E282DDE55}" />
    <EventID>1</EventID>
    <Version>0</Version>
    <Level>2</Level>
    <Task>1</Task>
    <Opcode>0</Opcode>
    <Keywords>0x8000000000000000</Keywords>
    <TimeCreated SystemTime="2010-04-27T21:21:44.407053800Z" />
    <EventRecordID>19</EventRecordID>
    <Correlation />
    <Execution ProcessID="2460" ThreadID="5960" />
    <Channel>Microsoft-Windows-UAC/Operational</Channel>
    <Computer>www2</Computer>
    <Security UserID="S-1-5-21-4017510424-2083581016-1307463562-1640" />
  </System>
  <EventData></EventData>
</Event>

The errors shown in the Task Scheduler History tab display these results and states

This operation requires an interactive window station. (0x800705B3)

EventID 103

Task Scheduler failed to launch action
"F:\App\Path\ConsoleApp.exe" in instance "{1a6d3450-b85a-40c0-b3db-72b98c1aa395}" of task "\taskFolder\taskName". 
Additional Data: Error Value: 2147943859.

EventID 203

Task Scheduler failed to start instance "{1a6d3450-b85a-40c0-b3db-72b98c1aa395}" of "\taskFolder\taskName"  task for user "LIVE\TaskUser" . 
Additional Data: Error Value: 2147943859.