Location not available: Desktop

I restarted my computer today, and when it turned back on it came with an error message saying

C:\windows\system32\config\systemprofile\Desktop refers to a location that is unavailable. It could be on a hard drive on this computer or on a network. Check to to make sure the disk is properly inserted.

All of my desktop and taskbar icons were gone, and my desktop seemed to revert back to Window 98. When I restarted my computer again half of my icons were back, but the desktop still looked like it was from 1998. When I went into the control panel to change the theme, it changed back to my windows 7 theme, but every time I restart the computer it reverts back to windows 98. Has anyone else had this problem/ is there a known fix for it?

Thanks for the response. If I do this will I lose my documents and stuff?

It says I need a windows 7 installation CD. I don't think my computer came with oneI

I tried to go to the desktop folders and select "restore default", and that didn't work. What is happening now is when I restart my computer it reverts back to windows classic and I get a message saying "User Profile Service failed to start". When I log off and log back onto my account twice, windows reverts back to normal. I am no longer getting the message that the desktop location is not available.

When I check the event viewer I get these error and warnings...

Log Name: Application
Source: Microsoft-Windows-User Profiles Service
Date: 8/20/2010 2:45:24 PM
Event ID: 1542
Task Category: None
Level: Error
Keywords:
User: SYSTEM
Computer: Tom-VAIO
Description:
Windows cannot load classes registry file.
DETAIL - The process cannot access the file because it is being used by another process.

Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<System>
<Provider Name="Microsoft-Windows-User Profiles Service" Guid="{89B1E9F0-5AFF-44A6-9B44-0A07A7CE5845}" />
<EventID>1542</EventID>
<Version>0</Version>
<Level>2</Level>
<Task>0</Task>
<Opcode>0</Opcode>
<Keywords>0x8000000000000000</Keywords>
<TimeCreated SystemTime="2010-08-20T18:45:24.777364300Z" />
<EventRecordID>19498</EventRecordID>
<Correlation />
<Execution ProcessID="988" ThreadID="736" />
<Channel>Application</Channel>
<Computer>Tom-VAIO</Computer>
<Security UserID="S-1-5-18" />
</System>
<EventData>
<Data Name="Error">The process cannot access the file because it is being used by another process.
</Data>
</EventData>
</Event>

Log Name: Application
Source: Microsoft-Windows-User Profiles Service
Date: 8/20/2010 2:45:24 PM
Event ID: 1508
Task Category: None
Level: Error
Keywords:
User: SYSTEM
Computer: Tom-VAIO
Description:
Windows was unable to load the registry. This problem is often caused by insufficient memory or insufficient security rights.

DETAIL - The process cannot access the file because it is being used by another process.
for C:\Users\Tom\AppData\Local\Microsoft\Windows\\UsrClass.dat
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<System>
<Provider Name="Microsoft-Windows-User Profiles Service" Guid="{89B1E9F0-5AFF-44A6-9B44-0A07A7CE5845}" />
<EventID>1508</EventID>
<Version>0</Version>
<Level>2</Level>
<Task>0</Task>
<Opcode>0</Opcode>
<Keywords>0x8000000000000000</Keywords>
<TimeCreated SystemTime="2010-08-20T18:45:24.777364300Z" />
<EventRecordID>19497</EventRecordID>
<Correlation />
<Execution ProcessID="988" ThreadID="736" />
<Channel>Application</Channel>
<Computer>Tom-VAIO</Computer>
<Security UserID="S-1-5-18" />
</System>
<EventData Name="EVENT_REGLOADKEYFAILED">
<Data Name="Error">The process cannot access the file because it is being used by another process.
</Data>
<Data Name="File">C:\Users\Tom\AppData\Local\Microsoft\Windows\\UsrClass.dat</Data>
</EventData>
</Event>

Log Name: Application
Source: Microsoft-Windows-Winlogon
Date: 8/20/2010 2:45:17 PM
Event ID: 6003
Task Category: None
Level: Warning
Keywords: Classic
User: N/A
Computer: Tom-VAIO
Description:
The winlogon notification subscriber <Profiles> was unavailable to handle a critical notification event.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<System>
<Provider Name="Microsoft-Windows-Winlogon" Guid="{DBE9B383-7CF3-4331-91CC-A3CB16A3B538}" EventSourceName="Wlclntfy" />
<EventID Qualifiers="32768">6003</EventID>
<Version>0</Version>
<Level>3</Level>
<Task>0</Task>
<Opcode>0</Opcode>
<Keywords>0x80000000000000</Keywords>
<TimeCreated SystemTime="2010-08-20T18:45:17.000000000Z" />
<EventRecordID>19493</EventRecordID>
<Correlation />
<Execution ProcessID="0" ThreadID="0" />
<Channel>Application</Channel>
<Computer>Tom-VAIO</Computer>
<Security />
</System>
<EventData>
<Data>Profiles</Data>
<Binary>D9060000</Binary>
</EventData>
</Event>

Log Name: Application
Source: Microsoft-Windows-Winlogon
Date: 8/20/2010 2:44:54 PM
Event ID: 6000
Task Category: None
Level: Warning
Keywords: Classic
User: N/A
Computer: Tom-VAIO
Description:
The winlogon notification subscriber <Profiles> was unavailable to handle a notification event.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<System>
<Provider Name="Microsoft-Windows-Winlogon" Guid="{DBE9B383-7CF3-4331-91CC-A3CB16A3B538}" EventSourceName="Wlclntfy" />
<EventID Qualifiers="32768">6000</EventID>
<Version>0</Version>
<Level>3</Level>
<Task>0</Task>
<Opcode>0</Opcode>
<Keywords>0x80000000000000</Keywords>
<TimeCreated SystemTime="2010-08-20T18:44:54.000000000Z" />
<EventRecordID>19491</EventRecordID>
<Correlation />
<Execution ProcessID="0" ThreadID="0" />
<Channel>Application</Channel>
<Computer>Tom-VAIO</Computer>
<Security />
</System>
<EventData>
<Data>Profiles</Data>
<Binary>D9060000</Binary>
</EventData>
</Event>

Log Name: Application
Source: Microsoft-Windows-CAPI2
Date: 8/20/2010 2:41:20 PM
Event ID: 4107
Task Category: None
Level: Error
Keywords: Classic
User: N/A
Computer: Tom-VAIO
Description:
Failed extract of third-party root list from auto update cab at: <http://www.download.windowsupdate.com/msdownload/update/v3/static/trustedr/en/authrootstl.cab> with error: A required certificate is not within its validity period when verifying against the current system clock or the timestamp in the signed file.
.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<System>
<Provider Name="Microsoft-Windows-CAPI2" Guid="{5bbca4a8-b209-48dc-a8c7-b23d3e5216fb}" EventSourceName="Microsoft-Windows-CAPI2" />
<EventID Qualifiers="0">4107</EventID>
<Version>0</Version>
<Level>2</Level>
<Task>0</Task>
<Opcode>0</Opcode>
<Keywords>0x8080000000000000</Keywords>
<TimeCreated SystemTime="2010-08-20T18:41:20.639661300Z" />
<EventRecordID>19468</EventRecordID>
<Correlation />
<Execution ProcessID="996" ThreadID="2196" />
<Channel>Application</Channel>
<Computer>Tom-VAIO</Computer>
<Security />
</System>
<EventData>
<Data>http://www.download.windowsupdate.com/msdownload/update/v3/static/trustedr/en/authrootstl.cab</Data>
<Data>A required certificate is not within its validity period when verifying against the current system clock or the timestamp in the signed file.
</Data>
</EventData>
</Event>

What do I do after creating a new account?