virus problem

[#1]

Avast recently identified a virus on my computer....trojan.agent 9216.121 and put it in the virus chest.
Since then I have been getting the following message when I log on......... Error loading C:\windows\system32NvCpl.dll
Once I click ok everything loads up and runs fine.
Should I just carry on and put up with this message each time I boot up or is there something else going on in my computer that I should be worried about ?
Once in the virus chest should it be left there or be deleted ?
There is a fair amount of info about this Trojan on the net when the first 4 digits are entered but add the last 3 digits and nothing helpful comes up.
Please keep replies simple as I know nothing about this topic.
Thanks 

[#2]

Sounds like it removed the virus but failed to remove the link to start it up in the registry.
Try running lavasoft's adaware and do a clean, or spybot search&remove (both should be FREE so if you get to a site that wants money you have picked the wrong link) just google for them.
These will clean the system for you.
You could just enter regedit (in the RUN box at start) and then search for the dll you mentioned, then delete the key but that can lead to more issues. 

[#3]

The file NvCpl.dll which its complaining about is for NVIDIA Display. There a a couple of way of sorting this out
1 download startupcpl from http://www.mlin.net/StartupCPL.shtml  It list the startup programs and you untick to stop them loading. Run this and find the file and untick it. Its not needed and will you ok without it. It will say C:\windows\system32\NvCpl.dll in the path and the file will probably be nvcpdaemon
2 Download the latest Nvidia drivers and install them as that will replace the file
3 If you have the Nvidia drivers on your cd that came with the pc you can find the file and copy it to the windows\system32 location
Dont do a system restore as this may well bring back the virus In fact the safe way is to remove system restore from the drive in the control panel which will delete all restore points as these may well still have the virus in them. Reboot and then put system restore back on and create a new restore point. You will loose all old restore point but you dont know how many are infected

[#4]

Samuria,
Thanks for your response. I Have downloaded and tried to run Startupcpl but just get the message error loading setupapi ?
I Have also downloaded the Nvidia drivers. Is it ok to go into the program files and delete the NvCpl.dll file  direct.
Thanks

[#5]

There are 2 startupcpls one is an exe the other is a cpl file download again and ensure you get the exe file. It sounds as if you have got the  one for the control panel  which must go into windows\system32 to work.
Yes you can delete the file if its there.
Loading the new drivers will replace the file so dont delete it if you have installed the new drivers.