Trojan Horse---Threat found

[jbm808]

So, my antivirus software Symantec detected through "Auto Protect Scan" that a threat has been found and it so happens to be indentified as the "Trojan Horse". It was located in a .dll area of my Cdrive, but was already quarantined. But I wanted to make sure by running a scan through all my drives and such. Obviously it found it and took the necessary steps to delete it following the scan.
But why does it still pop-up a window about detecting the "Trojan Horse" again..was it not deleted the way it should have been? Did I not delete it correctly?

I've also noticed that when my computer starts up and loads my icons onto my taskbar that it will pause for about 2mins before resuming (maybe just a slow processor to begin with) but also has had an affect on my internet surfing...been dragging..does this have something to do  with Trojan or is it that time for my old computer to get an upgrade?

so confused on what to think of this..
fyi: comp specs...still running on a compaq presario mv520 back in 2000!!! probably a 16-bit at that..(sad, i know..)

[dl65]

 jbm808.... Norton ,may have quarintined the trojan but it may not have been able to remove it ....so the first thing to check is ...... open Norton , go to the quarinte file  ....reports ..... then click on activity threats and see if the threat that was detected was removed or it the removal failed ....... Norton , while very good in dealing with vires , doesn,t do so well with trojans ........
If you see the trojan in the quarintined file ...... delete the etry there and then do this ......
1   Turn off system restore on all drives.
2   Go into the control panel .... folder options/view ........ and tick show hidden files and folders ..... then click apply and ok
3 Go to ... http://www.filehippo.com/download_ewido/   and d/l Ewido v3.5
4 reboot into Safe mode ......
5 Scan your system with Ewido ...and remove anything it finds .
6 Run a full system scan with Norton ....... just to be sure things are clean....
If things are clean , reboot back into normal mode and turn system restore back on .......

dl65