Vista - Windows won't allow more windows

After opening several windows in IE 7, after a while a window will open but
will not load. If I close a previous window, sometimes the new window will
work on a second try, but the problem repeats until I can open no windows at
all. I understand there's a memory issue with opening lots of windows, but
after I've closed them all, I often can't even open a Folder Window, or even
right clicking displays a tiny blank box instead of options. Even dialog
boxes are limited once it reaches this point. After a reboot, everything's
back to normal, until I go back to the internet.
I've disabled Google Toolbar to no avail.
I'm currently running Vista Home Premium, AMD 64 X2 Dual Core 4800+ 2.5 GHz
2GB Ram
Norton Internet Security
Any ideas?