Server 2008 locks me out when not using the machine for 10 minutes after installing SP2

Check the group policy for your account.

• type gpedit.msc into the start search box and hit enter
• navigate to User configuration -> Administrative templates -> control panel -> display
• Change screen saver to disabled, and screen saver timeout to a high value just in case.

What worked for me, was similar to the above...

In gpedit, navigate to Computer Configuration -> Windows Settings -> Security Settings -> Local Policies -> Security Options -> Microsoft network server: Amount of idle time required before suspending a session

then reset the timeout to the desired value in minutes.