In October 1, 2010, Intel released a document that describes design defects, known errors, and all the stuff that can make a sysadmin’s life a pain. It was an specification update for the Intel 82546GB Gigabit Ethernet Controller (e1000 driver for most *nix implementations).
This ethernet controller is a pretty common chipset, dual ports cards (copper). This chipset was released in April 1, 2004. Yeah, seems like a joke…
If you have this chipset running on desktop or servers you should look at the document 82546GB Gigabit Ethernet Controller Specification Update, and see if your driver has the “workarounds” described on this document (for some issues), or maybe has a configuration option to change some features and try to deviate from the problems (options that driver’s engineer cannot choose for you).
This Errata has 18 points, and i will list here some:

LSO Premature Descriptor Write Back;
Message Signaled Interrupt Feature May Corrupt Write Transactions;
Inbound and Outbound reads not fully decoupled in PCI-X mode;
Hang in PCI-X systems due to 2k Buffer Overrun during Transmit Operation;
PCI-X Arbitration Interaction with Particular Bridges Can Result in Controller Hang;
Transmit (Tx) Hang on GMII/MII Interface at 10/100 Mb/s Speed;
No PCI-X Transmit (Tx) or Receive (Rx) DMA Activity From the 82546GB

You will find many mails on OpenSolaris and GNU/Linux forums about problems with Intel drivers, and OpenSolaris has many options (obscure ones), to disable and i think try to deviate from some of the problems described on the above document.
I think manufacturers did know about that problems before us, but as many are “big ones” on the chipset design, i don’t know what efficient the driver can be to avoid them.
Would be really nice to hear from the Network Hackers from OpenSolaris/Solaris kernel if the e1000g driver has the fixes for the problems described on this document (Intel has no plan to fix them), and to know the list of options the e1000g driver has (actually is a tough work to decouple this options from the source).
Well, hope this can help you if you have problems with this intel chipset, performance or hang issues, and even look for other similar contents from Intel about ethernet controllers so “blind” used in these days. Maybe your problem is down there…