HDMI causes freezing?

A curious thing has happened. I have a Dell Studio 540.  I hooked up my monitor via HDMI cable, and everything looked fine.  When I 'wake up' the screen from powersaving mode/screensaver the screen is frozen for several minutes.  The mouse can move freely but nothing responds to keyboard or mouse clicks. This kept happening after a wake up. I switched back to a standard VGA cable and the problem is gone.  Anyone know why this happened with HDMI? Is it even worth it to use HDMI for computer monitor?  Thanks

Kyle