Http and SQL problems

I run a game/3D world on my network.
One morning a week or so ago I stopped receiving any new sign-ups and people began complaining that several of the sites web pages wouldn't load and the 3d objects and textures in the world were not downloading at the normal speed and were timing out.
I am running a windows 2003 server with SQL, IIS and the game on it.
I suspected it was the old C: drive failing so I bought a new computer, installed 2003 on it and all of the other programs and copied the datafiles over to it and the same exact problems still exist.
I've run 2 or 3 different virus scanners, spyware scanners, firewall programs, defragged, ran chkdsk, called my ISP, I've run download tests for speed and everything checks out ok.
I suspect someone is hacking the system and causing specific pages not to load and causing the objects not to download correctly. The game pulls them from a directory on the webserver.
Everything works fine for me on the network. All of the pages load fine. Everything downloads fine in the game.
I've uninstalled and re-installed IIS 2 or 3 times.
I noticed that there are 2 winlogon.exe's running in taskmanager
If there are any IIS/SQL experts out there that might have a clue I really need help getting things running well again!