Try throwing out the City of Heroes Preferences (yes, again) but before you do that, run Disk Utility (Applications > Utilities > Disk Utility) and Repair Permissions.
Manga @ Triumph
"Meanwhile In The Halls Of Titan"...Titan Network Working To Save City Of Heroes
Save Paragon City! Efforts Coordination
What type of mods were you refering to?
I'm running Mac OS 10.5.6 on a Mac Pro 2,66GHz Quad-Core Xeon with 6Go of DDR3 RAM. As far as I know it's pretty much straight out of the box, barring the upgrades the Apple Store put in it before it was delivered. It's on a network with other macs but hardware-wise it's pretty standard.
Netphenix5