The HDD of the server was out of disk space, and after a reboot, RRAS won't start anymore on my 2008 R2 server.

Error Details:

Log Name:      System
Source:        RemoteAccess
Date:          2/5/2012 9:39:52 PM
Event ID:      20153
Task Category: None
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      Windows14111.<snip>
Description:
The currently configured accounting provider failed to load and initialize successfully. The connection was prevented because of a policy configured on your RAS/VPN server. Specifically, the authentication method used by the server to verify your username and password may not match the authentication method configured in your connection profile. Please contact the Administrator of the RAS server and notify them of this error.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="RemoteAccess" />
    <EventID Qualifiers="0">20153</EventID>
    <Level>2</Level>
    <Task>0</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2012-02-05T20:39:52.000Z" />
    <EventRecordID>12148869</EventRecordID>
    <Channel>System</Channel>
    <Computer>Windows14111.<snip></Computer>
    <Security />
  </System>
  <EventData>
    <Data>The connection was prevented because of a policy configured on your RAS/VPN server. Specifically, the authentication method used by the server to verify your username and password may not match the authentication method configured in your connection profile. Please contact the Administrator of the RAS server and notify them of this error.</Data>
    <Binary>2C030000</Binary>
  </EventData>
</Event>

I think it has something to do with a corrupt config file, but I am unsure of what to do. I Removed the RRAS role, rebooted, and re-added, but it keeps failing with the same error.

Thanks in advance.

[UPDATE]

If i set the accounting provider from 'Windows' to '' the service starts but VPN won't work. Any ideas how this can be repaired?