To increase this time out:
Click System.
Within the Options drop down menu, click System Control Options.
On the System Format tab, next to System E-mail Defaults, click the blue arrow icon. The System E-mail Defaults screen appears.
In the top left, click the computer icon.
In the Timeout in ms field, change the number to something that is applicable to the user.
Click Save on all 3 screens that are currently open.