Thank you for your reply
Before you try the Recovery Console ...
If the f8 "last known good" is not working, you can launch System Restore this way:
When you press f8, choose safe mode with command prompt
1. Your computer will then boot to a command prompt (dos window). C:\....... you want to note what comes after the c:\ because you may need to change the default directory.
2. Change the directory by typing.
cd c:\windows\system32\restore\ Then press the Enter key.
3. Then press the Enter key.
4. Type: rstrui.exe
A couple of other things come to mind.
Are you using a D-Link network adapter?
If so, use the XP device manager to disable the "4X Mode" and see if that stops the MTU from being reset.
I assume when you change the MTU with TCP Optimizer you are selecting to change the correct adapter :-)...I only mention this because I made this mistake myself when I first used it.