Trouble with Wake on LAN and Wake on Ring

I have a a Dell Optiplex 755 with WinXPPro SP3, 2GB RAM and an Intel Core 2 Duo E4600, and it is unreliable for Wake on LAN and Wake on Ring.

When the PC is in sleep mode (S1 or S3), they work some of the time but not all of the time, and I'd like them to be 100% reliable.

These may be two different problems, but your advice will be appreciated. (Also, if I should post in a different forum, please advise.)

My Network Card is an Intel 82566DM-2 Gigabit Network Connection, and I recently upgraded its drivers using "generic" PROXP.exe from the Intel website although this has not helped the problem. When I'm on the computer, I don't feel or see a difference - the network and internet link seems to be working well, same as before. The specific driver file e1e5132.sys is now version 9.12.36.0 from 2008 -- it used to be version 9.8.20.0 from 2007. But, as I say, Wake on LAN from Sleep was not and is still not reliable, before and after the driver update.

In Settings .. Network Connections ... Local Area Connections ... Properties ... Configure ... Power Management, all the Wake on LAN options are checked ON:
- Wake on Directed Packet
- Wake on Magic Packet
- Wake on Magic Packet from Power Off Sate
- Wake on Link

The NIC card's Diagnostic checks are all OK.

My BIOS is version A14. I have a choice of S1 or S3 for Sleep, and the problems are the same regardless which one I choose.

My fax modem card is Conexant D850 PCI V.92 Modem, and I have recent drivers dated 7/27/07, version 7.67.0.50. In Settings ... Phone and Modem Options ... Modems ... Properties, "Allow this device to bring the computer out of standby" is checked ON.

What to do? If it's a BIOS problem, how can I fix?

Thanks.