Detecting fraud on your computer

Start with things like Malwarebytes or Spybot Search and Destroy and see what they turn up.

A "Backdoor Trojan/Bot" such as SDBot is able to steal your personal information. Kasperky explains it:
Viruslist.com - Backdoor.SdBot.gen
http://www.viruslist.com/en/virusesd...pter=153313132

I would reinstall the system. Just to be on the safe side. And have all the data you save scanned here. That may be a little cumbersome, but it is the most radical solution. Then, of course, you want your bank to take the appropriate actions to protect your account.

These are the most dangerous, and most widespread, type of Trojan.
Backdoor Trojans provide the author or ‘master’ of the Trojan with remote ‘administration’ of victim machines. Unlike legitimate remote administration utilities, they install, launch and run invisibly, without the consent or knowledge of the user. Once installed, backdoor Trojans can be instructed to send, receive, execute and delete files, harvest confidential data from the computer, log activity on the computer and more.
If your computer was used for online banking or has credit card information on it, all passwords should be changed immediately to include those used for email, eBay and forums.
You should consider them to be compromised.
They should be changed by using a different computer and not the infected one... if not an attacker may get the new passwords and transaction information.
Banking and credit card institutions should be notified of the possible security breech.

The best course of action would be a reformat and reinstall of the OS.
More info can be found below:
How Do I Handle Possible Identify Theft, Internet Fraud and CC Fraud?
How to report ID theft, fraud, drive-by installs, hijacking and malware? Security - dslreports.com

Also a possibility of a keylogger that's not being detected. But it's also possible it wasn't accessing it from your computer.