Why does a network drive fall off on Windows 2008?

Question

Samba

Good afternoon!
Given:
Free version of Vmware vSphere 4 Hypervisor
Virtual machine running Windows 2008
A folder with an ancient file database is shared over the network on a virtual server
50 clients use this folder as a network drive.
Problem:
The network drive is inaccessible for a few seconds and all clients fail with an error.
Frequency - a couple of times a week at different times.
What changed before the errors appeared:
1) Replaced the root switch of the network
2) Several more IP addresses were added to the settings of the only virtual server network card.
Before the errors appeared, there were several IP addresses on the network card for more than a year, but, apart from the main one, they were hardly used.
3) Age of iron - two years.
In the logs of Windows 2008, I did not find anything clearly indicating errors
Question:
How to find the cause of the problem? What to look for in the logs? What do you need to start logging?

Answer 1

The problem was in the root switch - they replaced the firmware and the problems ended

Answer 2

Try adding a second virtual network card and transfer all non-primary IPs to it.

Answer 3

And what is in the logs on the PC when the disk fell off, and the virtual machine is available at that moment? Is there a ping on it?