Detected but not removed virus

First of all, sorry for my poor English, but it's not my first language.

 

I've Norton Antivirus 2006 installed in a PC with Windows XP. I'm suffering some problems:

- The right click is disabled.

- When I connect to the Internet via telephone (low bandwith) I lose control of the connection. I cannot access the connection properties (it hides quickly).

- I cannot navegate to webpages of antivirus or security.

- The system restauration tool is disabled.

- Using the msconfig tool, in the startup there's a call to tskmngr.exe (not the taskmgr.exe Windows task manager).

 

After updating the definitions by executing th file in http://www.symantec.com/business/security_response/definitions/download/detail.jsp?gid=n95 the Norton Antivirus finds two risks:

 

SecurityRisk.URLRedir
 Id. del virus: 4294909963


W32.Spybot.Worm
 Id. del virus: 34750

 

It seems the antivurs cleans the risks and ask for a reboot. I do it and launch another scan. Then I have the same virus detected and sometimes is detected also

 

W32.IRCBot.Gen
 Id. del virus: 26828

I am rebooting and scanning for days, updating the antivirus definitions via the file dowloaded in another PC.

 

Another thing: In the c:\windows and in c:\windows\directories there're some new files. Norton doesn't iddentify them as malware or virus, but I copied the to a CD and scanned in another computer with another antivirus and identified them as trojan win32.buzus.ah.

Why an updated Norton antivirus doesn´t see them as trojans?

 

Please, could you help me?

 

Thanks in advance.