Upgraded from win98 to windows2000

I am using a Compaq Tower Deskpro. Just upgrade to windows 2000 which runs pretty ok. However, i am having problems
1. I have lost internet access via the proxy sever
2. I cannot Re install the CD writer software
3. I used to communicate with other cliets through winpopup it is not possible now
and 4. iam using Noton but the defination date is not visible

thank you