Is your computer updated for all critical updates including SP2 and the subsequent updates?
If it is not, and you are certain you are free of malware (although I don't see how you can be running on a DSL modem with no AV program initially), update to all available updates immediately.
(I would recommend you post a HJT log before doing so, but if you are sure your computer is clean - download and install all the MS Critical Updates, setting the updates on Automatic download and install for a time you know the computer will be on and connected to the net.
You also need some additional malware protection, starting with a two way firewall instead of the puny one way XP firewall:Freeware AntiSpyware and Security ProgramsSoftware firewalls with freeware versions
Zone Alarm: http://www.zonelabs.com/store/content/cata...g=en&lid=nav_za
(you can have only one software firewall running. More than one will conflict)Anti-malware freeware
(You can run as many of these as you wish. Generally there is no conflict between these and you should always run several)
Ad-Aware SE Personal is a free version and it can be downloaded from our Mirror Sites in the Download section at Lavasoft website. However, please note that while the free Ad-Aware SE naturally helps you remove all spyware, it does not provide real-time memory scanning; this capability comes with the paid versions.http://www.lavasoft.com/
Click on Adaware SE Personal in “Products” on the left side of the page
Spybot S&D: http://www.safer-networking.org/en/index.html
Be sure to enable “Teatimer” which gives you realtime protection.
Microsoft Windows Defender http://www.microsoft.com/athome/security/s...re/default.mspx
This also provides realtime protection.
Microsoft Malicious Software Removal Tool (Win XP and Win 2000):http://www.microsoft.com/security/malwareremove/default.mspx
A˛ - Free from http://www.majorgeeks.com/download4281.html
. Run it, click Search for Updates, then click Scan.
Microsoft Baseline Security Analyzer (MBSA)
MBSA is an easy-to-use tool designed for the IT professional that helps small and medium businesses determine their security state in accordance with Microsoft security recommendations and offers specific remediation guidance. Improve your security management process by using MBSA to detect common security misconfigurations and missing security updates on your computer systems.http://www.microsoft.com/technet/security/...a2/default.mspxWeb based online Antivirus and anti-malware scans:
(these can be run regardless of whatever else you are using. You must use Internet Explorer to run these.)
Kaspersky Anti-Virus Web Scannerhttp://www.kaspersky.com/service?chapter=161739400#betatest
Panda Activescan http://www.pandasoftware.com/activescan/co...n_principal.htm
Trend Micro antivirus and malware scan:http://housecall-beta.trendmicro.com/en/st...orp.asp?id=scan
Trend Micro antivirus European Edition (supports Mozilla based browsers)http://uk.trendmicro-europe.com/consumer/h...call_launch.php
Etrust Anti-virus web scannerhttp://www3.ca.com/securityadvisor/virusinfo/scan.aspx
online trojan scans here - http://scan.sygatetech.com/pretrojanscan.html
Windows Security Trojanscanhttp://windowsecurity.com/trojanscan
See instructions for it here: