Network connection randomly dropping

[Guest2]

We have a Dell Optiplex 780 machine running Windows 7 32bit which has an Intel(R) 82567LM-3 network adapter. It randomly doesnt connect in the morning. A restart or log off, then back on usually sorts it and its fine again. Is it possible to set the flow speed of the adapter some how? I have found flow control but it has no speed settings.
Its strange because we have 2 other identical machines that have no problems. I have disabled the power options so the adapter is not turned off automatically but this hasnt sorted (nor does it need turning off on the other 2 machines)

As it's in the morning, could it possibly be something to do with the computer maybe going into sleep mode after it has automatically turned on from bios at 6am? I'll check again but im sure I turned sleep mode off on all 3 machines

 

[PatZ1989]

There's a few things it could be, sleep mode would be the whole computer as opposed to the network adapter, check any BIOS power saving options for disabling the NIC.

 

[nrh1703]

slightly different set up but we had a couple of optiplex 745s with broadcom nics that had drop out issues. it seemed to be random and even had a replacement motherboard. It turned out to be a problem with MS Virtual PC and Virtual Server and the nic drivers. We updated them and the problem went away.