Vista - DHCP Client Stops

Our company has decided to 'dip its toe' into the world of Microsoft Vista.
We purchased a HP Compaq dc7700 Small Form Factor with Vista Business as an
evaluation machine. The PC was initially connected to our Domain, obtaining
its IP address automatically.

However during the day the system went into hibernation and when it resumed;
all network/internet connection was lost. A check of Services revealed the
DHCP Client had stopped. Tried restarting the service but we receive an
'error 5' message?

Our network administrator and I are completely baffled on this matter. Has
anyone else been confronted with the same issues and what steps did you take
to overcome them?

All assistance is greatly appreciated.