GSM7248 - intermitent ping failure

Hello,

I´ve been killing my head, and probably this is something very simple that i am cannot see.

I have a problem with intermitent connection and this is what happened from start.

Network is:

GSM7248 + GS724T + GS724T

Have one Server with a network card with 4 ports that had Windows Installed. Everything was working fine.

We installed Esxi at this server and when we try to manage it, we noticed some connection breaks. 

This server is connected to the GSM7248

Also, there is great number of other Server, Vlans, etc working at this Switch without any issues.

When we ping the server few pings ok, few other fail. (its 4 to 6 of each, sometimes shorter or longer quantity, totally intermitent. 

First thing we thought, was server network card broken, so we tested with laptop connected directly to each of the ports of the network card, and they all work perfectly and you could ping all fine.

So this is strange and breaking my head:

Server connected to GSM7248 with Network card port 0, Hell breaks loose, intermitent ping failure, doesnt matter from where i am pinging

Server connected to GSM7248 with Network card port 1,2,3 work fine and perfect

Server connected to GSM724T with Network card port 0, works good if i have also my laptop connected to the GSM724T

But if i connect Laptop to the GSM7248, same intermitent connection problem occur.

I tried with different IP address (Not that it could be the problem). I am sure there isnt any duplication.

I have tried different ports in all switch, always same behaviour.

Thank you for any help.