Network connection from old application to SQL Server 2008 R2 lost once in a while I have put this question on serverfault.com as well, but since the problem concerns connecting to SQL Server, I will also put it here.

We are trying to migrate an Axapta 2.5 database from SQL Server 2000 to 2008 R2. We are testing performance etc. on the new server, but once in a while, these two events are thrown on the Axapta server:


  Object Server SandBOX: The database reported (session 11 (CSS)):
  [Microsoft][ODBC SQL Server Driver]Communication link failure. The SQL
  statement was: ""


and


  Object Server SandBOX: Fatal system condition - quitting for restart
  due to lost database connection.


after which all clients have to reconnect.

The Axapta 2.5 server is a virtual server (VMWare) running Windows 2003 SP2. 
Info from vSphere:


VM Version: 7
CPU: 1 vCPU
Memory: 1024 MB
VMNetwork: VMXNet 3


The SQL Server is also a virtual server (VMWare) running Windows 2012 R2.
Info from vSphere: 


VM Version: 8
CPU: 4 vCPU
Memory: 73728 MB
VMNetwork: VMXNet 3


There are no traces of an error in either the event log on the SQL Server or in the SQL Server Logs.

When searching the internet for a solution, I only found one with this exact problem, and it had no answer (how to troubleshoot sql 2008 dropping connections on sqlservercentral.com). I mostly see suggestions around the virtual network adapter or settings on the virtual server, for more or less similar problems.
I'm probably forgetting a lot of information, but I'm actually a DBA, so bear with me.

I know very little of virtual machines and network. Thanks for your help.
Could anyone point me in a direction with this issue?
Axapta 2.5 was not supported on SQL Server 2005 or later versions so you are out of your depth there. To support later version of the database engine you will need to update the axapta application itself. 2.5 predates SQL Server 2005 by years: http://everything.explained.today/Microsoft_Dynamics_AX/

Any problems you have with incorrect statements are most probably due to the axapta server getting confused over the database version, you could try to change compatability level to 8.0 but I would recommend that you contact an Axapta certified partner and migrate to newer version of the application