Currently playing with Windows OS.. works perfectly.. but since yesterday when i opened vendetta.exe.. it responded like this in the "vendetta update utility" popup box

Checking update program...
Connecting to update1.vendetta-online.com:21024...
Failed connecting to update1.vendetta-online.com

You might simply try again, the update server could have been offline or restarting for some reason. If it still doesn't work, check that your antivirus hasn't forbidden VO internet access.