SQL Server crashes on Cluster

In the last two weeks, a problem appeared on my 3 node SQL Server 2012 (SP1 CU2) on Windows 2008 R2 Cluster:

The database engine intermittently crashes with the following error message:

Faulting application name: sqlservr.exe, version: 2011.110.3339.0, time stamp: 0x50f51be9

Faulting module name: KERNELBASE.dll, version: 6.1.7601.18015, time stamp: 0x50b8479b

Exception code: 0xc0730003

Fault offset: 0x0000000000009e5d

Faulting process id: 0x1ab0

Faulting application start time: 0x01ce8c5196e67f51

Faulting application path: C:\Program Files\Microsoft SQL Server\MSSQL11.MSSQLSERVER\MSSQL\Binn\sqlservr.exe

Faulting module path: C:\Windows\system32\KERNELBASE.dll

Report Id: b991091e-f8eb-11e2-9818-e61f133bacfb

The error occurs on all nodes and the exception code and fault address are always the same.

How can I narrow down this issue?

Thank your for your replies

     tom