Hello Armando, this file should belong to Intego virus barrier app.
The best thing to do appears to be setting Intego VirusBarrier to "trust" the folder, or its enclosing folder, preferably before encrypting it for the first time. Encryption then appears to behave normally with VirusBarrier running.
If the folder was previously encrypted (perhaps with an earlier version of Espionage) or was under the "protection" of any version of VirusBarrier at any time in the past, then the .vbt5 invisible file must be removed before the file can be encrypted. Using iVisible (you can find it on macupdate) to make .vbt5 visible and moving it only to the trash fixes the problem and it doesn't recur.
Let me know how it went,
Rgds
Zsolt