SQL Server keeps losing drive letter

Hi

This is a virtual server, that until today had no problems I am aware of.

I have the OS installed on C and a seperate virtual drive for the actual DB (B:\)

Everytime I reboot the DB Drive is missing its drive letter. Even after I reassign it, I cannot start the SQL service - error in eventlog:

Log Name:      Application
Source:        MSSQLSERVER
Date:          16/05/2011 14:45:38
Event ID:      17053
Task Category: Server
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      Saints-SQL.Saints.local
Description:
FCB::ZeroFile(), GetOverLappedResult(): Operating system error 19(failed to retrieve text for this error. Reason: 15105) encountered.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="MSSQLSERVER" />
    <EventID Qualifiers="49152">17053</EventID>
    <Level>2</Level>
    <Task>2</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2011-05-16T13:45:38.000000000Z" />
    <EventRecordID>6947</EventRecordID>
    <Channel>Application</Channel>
    <Computer>Saints-SQL.Saints.local</Computer>
    <Security />
  </System>
  <EventData>
    <Data>FCB::ZeroFile(), GetOverLappedResult()</Data>
    <Data>19(failed to retrieve text for this error. Reason: 15105)</Data>
    <Binary>9D420000100000000B0000005300410049004E00540053002D00530051004C00000000000000</Binary>
  </EventData>
</Event>