The following was Carbonite Support's response to my question. I followed the steps and the problem resolved. I don't know what sort of security issues might result from turning off the user account control, but for now I'm going with it.
We apologize for the inconvenience. Such issues occur in Windows Vista due to its feature "User Account Control". User Access Control for security purpose limit application software such as Carbonite to standard user privileges until an administrator authorizes an increase in privilege level. Please perform the following steps to turn of User Account Control (UAC) and then, check your issue.
Click Start and then open Control Panel.
In the Control Panel, click User Accounts and Family Safety.
Click User Accounts.
Click Turn User Account Control on or off.
Clear the tick or check mark on the box beside the Use User Account Control (UAC) to help protect your computer option.
Click OK.
When prompted, restart the computer. Note that the changes will affect all users on the computer.
To enable the UAC, simply tick or select the checkbox again.