Microsoft Windows 7 Upgrade

I am experiencing problems with my Windows 7 upgrade. My system freezes especially from the Sleep mode and it takes about 15 minutes to actually get to my desktop. Has anyone else had that problem? If so, how was it corrected. The Microsoft techs seem to be in another zone when it comes to getting the system up and running. By the way,the upgrade was from Windows Vista Home Premium to Windows 7 Home Premium.