The 'Small' trojan downloader family consists of more than 370 different variants (info by June 28th, 2004). The main characteristic of these downloaders is that they are very compact (a few kilobytes long) and that they hiddenly download and run executable files on a user's computer.
Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.
A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:
Check for the latest database updates
First check if your F-Secure security program is using the latest updates, then try scanning the file again.
Submit a sample
After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.
Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.
Exclude a file from further scanning
If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.
Note: You need administrative rights to change the settings.
Many of these downloaders are compressed with different file compressors to reduce their size and to hide their contents from users' eyes. Some of the downloaders from the 'Small' family download adware/spyware, searchware (third-party search plugins), some of them download real trojans and backdoors. But they all do that without any notification to a user and without his approval.
Quite often these downloaders are dropped and activated on users' computers from webpages that are visited with Internet Explorer.
For the generic description of a trojan downloader and for disinfection instructions for this type of malware please refer to this webpage:
Http://www.f-secure.com/v-descs/trojdown.shtml