Did this occur immediately after installing Windows 7?
Do you recall making any changes to your system or installing any software that may have caused this issue?
Before shutting down, right-click on the taskbar and bring up Task manger.
see if there are any programs running that you have previously closed out.
For example iexplore.exe and/or Firefox.exe
Please fill out your computers specs in the User Control Panel here on the site as well. It will then appear next to your name. look at my posting and you'll see the drop-down arrow.