My setup:

Server
SlimServer Version: 6.5.5 - 15249 - Windows XP - EN - cp1252
Running on Intel Q6600 no overclocking, motherboard Gigabyte GA-P35-DS4 rev. 2.0, 2 GB 6400 RAM. Windows XP Professional SP2.
Network adapter Linksys EG1032 v3 with latest drivers.

Squeezeboxes
Squeezebox 2 - firmware 81
Squeezebox 3 - firmware 81

Router
All connected through 3Com OfficeConnect Secure Router (3CR860-95), running firmware 1.04. Server and Squeezeboxes are running with fixed manually assigned IP on the same subdomain (192.168.1.xxx). Actually, I have completely disabled the router DHCP functions.

I followed the instructions and the network adapter is set with the "Allow this device to bring the computer out of standby” and “Only allow management stations to bring this computer out of standby” options activated.

I have verified that the machine works correctly with WOL, waking it up from my HTPC using Simplyware's WOL program.

If I have the two Squeezeboxes on Squeezenetwork, the computer goes to sleep (S3 Suspend to RAM) with no problem and remains that way. If I go back to Slimserver, once the Squeezeboxes send the magic packet (Waking up Slimserver...), the server wakes up correctly and all is good.

The problem arises when I have the two SBs connected to Slimserver and I try to have the server go to sleep. The machine prepares for standby, goes to standby and a split second later it tries to restart (which actually has negative consequences because it then enters into a strange loop of "on/off/on/off/etc.", probably not having had enough time to properly go to sleep).

I am 100% sure this depends on SBs because, as I mentioned, if they are on Squeezenetwork, or disconnected from the network, the server goes to sleep just fine, remains asleep with no problem and wakes up correctly with WOL capabilities (eg. my HTPC).

I have already formatted and reinstalled XP from scratch, just to be sure. Now I ask for help, 'cause I think I've tried pretty much everything.