It looks like a new version of your antivirus came out in feb is that the one your running?
Symantic threat resource virus/trojen list
That low or no memory warning (try disabling your antivirus etc before running it)
also try rebooting into safe mode & running antivirus/antispam programs that way.
The term Trojan horse or Trojan comes from Greek legend. In the world of computers, it refers to covert infiltration by malware or malicious software under the guise of a useful program.
After a Trojan is activated, it is often very difficult to discover the extent of the damage and generally identify the malware. The Trojan may change its original name and reactivate every time a PC is restarted.
In general, it's rare for a large number of files to be infected. Instead, the Trojan embeds itself directly in the computer's operating system. Depending on the motivation of the virus author, the malware contained in the Trojan may be designed to collect personal or financial data.
trend's defination of a trojan