I use ClamWin as my outlook virus scan. It has been working fine. Somehow today I got something from email which cause my system with alot of .exe no-disc error. I checked online. It's kind of very traditional Trojan virus. I have no other way but to reinstall the system. Just wondering why ClamWin didn't catch it. I think ClamWin scans every incoming email. I installed correctly with no problem integrated with outlook and IE.

Please advise how can I avoid this. There is not any warning from ClamWin at all. Thanks.

it's really hard to tell what went wrong from your description.
What is the exact error message?
What is your operating system?
What result do you get when you scan your whole drive c: with clamwin?

Was your ClamWin signature database current when you did the scan in question? If it was, when ClamWin failed to find the virus and you identified it, did you send a copy of the infected file to Clam at https://cgi.clamav.net/sendvirus.cgi so they could update the Clam/ClamWin signatures? You may have been the first Clam/ClamWin user to spot it. Some malware authors change their malware very often to escape signature identification.

Regards,