After doing some investigating, Bleeping Computer describes this as a undesired start-up program that is nasty. "W32/RBOT-GBY"- WORM/IRC- Back-Door. This seems to be a Legitimate virus/worm.
You can go to: http://www.microsoft.com/security/portal/threat/threats.aspx and type in the above given name, and it reveals the many different classifications.
I would also run the latest McAfee Getsusp Tool, and include your email in the "Preferences" box, and the file may indeed be detected,and sent to the McAfee Global Threat Intelligence Base. This is a quicker way of submission of files. I would also recommend running the Latest McAfee Stinger in "Safe Mode w/ Networking"
Google is your friend.....if you search "Cronos.exe" it will take you to the BC description.
One link recommends the Kasperky TDSS Tool, followed by Malwarebytes (Free).
Also the bottom link in "Ex_Brits" profile has superb free Anti-Malware tools.
I might add that if you scroll down this page, and look to the (Left) under "Top Liked Content" it has a link to the same Tools.
I hope this helps....