have you deleted the temporary files on your system? If not, try
these steps from microsoft
or you can use ccleaner from ccleaner.com and it will auto delete the temporary files on your system.
If that does not help, go to your task manager and click on the performance tab, post the info under physical memory.
Is office 2007 a new install or did the problems seem to start after installing it?
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there's been global warming since the ice age