Hi,

> I downloaded FB 2.5.5 from firebirdsql and my Microsoft Essentials
> detected it as a malware.

I am facing the same problem.
The following file is affected:
http://sourceforge.net/projects/firebird/files/firebird-win64/2.5.5-Release/Firebird-2.5.5.26952_0_x64.exe/download

This seems to be a false alarm though.
According to Virustotal, 54 different scan engines say the file is
clean:
https://www.virustotal.com/de/file/e4ce70fd1be17b07fd26554ef322ee14f65fef8d398aaa707df115530aa0f410/analysis/

Funnily, the Microsoft scan engine at Virustotal also considers it as
clean.


Cheers,
Christian