Issues running in vmware

[JJB7]

Microsoft Windows Server 2008 R2 x64
2 vCPUs @ 2.93GHz & 8GB RAM
Microsoft SQL Server 2008 R2 SP1 Standard Edition x64
ESX 4.1

I'm currently running a virtual environment with the above configuration. I'm experiencing instability on the server whenever I try to run a restore. Scenario is as follows:

Create database < ok
Backup database < ok
Restore backup < ok
Virtual restore backup < at this point the environment loses all connectivity with it's disks and hangs for about 30 seconds before being forced to restart by vSphere.

Has anyone experienced issues similar to this?