Win 2008 R2 server with Exchange 2010 randomly rebooting without warnings

Hi everybody, I have a strange case with my Exchange 2010 Server installed on Windows Server 2008 R2, it keeps rebooting here and there through the day without warnings. I can't see why it reboots itself like this.

Intel XEON 2.33 Ghz E5410
16Gb of RAM
HP 

When I go to the event viewer, I see 2 errors that comes frequently;

• The following fatal alert was generated: 10. The internal error state is 1203.
  
  
• The event logging service encountered an error (res=3) while initializing logging resources for channel DFS Replication.

The first error comes very often, the second one is there, but less than the first. I've searched the web and can't find why this occurs and if it's related. Where should I search, what should I do?

Thanks a lot for support!