If you're using BitDefender 2010 (and perhaps earier) do this:
Right click the BitDefender icon in the system tray (bottom right of the task bar)
Click on Settings to open the User Interface Settings window/box (top right)
Swithch UI to Expert mode
Close the User Interface Settings box
Click on Antivirus
Click on the Shield tab
Click on Advanced Settings to open BitDefender Active Virus Control Settings.
You need to add Chrome to the Exclusions list.
Click on the "+" button to give you the Open executable files window/box.
Navigate your way through the folder hierachy to C:\Documents and Settings\[Your Windows User Account]\Local Settings\Application Data\Google\Chrome\Application\Chrome.exe
Click on the Open Button
Chrome is now in the Exclusions list and should now work perfectly.