Empty System Temp Files
Run Disk Cleanup
Verify DNS settings for machine are set for local DNS server (or gateway) and not external DNS sites
If the machine has a wireless card, verify that the wired connection and wireless connection are not both getting an IP address (if connected via wired, turn off the wireless)
Analyze hard drive thru Defrag utility and defrag is needed
If domain controller is W2K mixed mode,
Go into your connection properties, and hit the properties button for TCP/IP.
Click the Advanced Button
Click the WINS tab.
In the NetBIOS settings, select Enable NetBIOS over TCP/IP.
Reboot
Review programs set in Programs\Startup folder
Review programs set in HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
And
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunOnce
Scan for malware/adware