My PC colleague had similar problems with VW2009 (constant freezing) and Ozcad had the following advice which fixed the problem:
"When something suddenly changes in the way Vw is operating, it is
usually due to either a corrupt file (if it only occurs in one file)
or with a stored setting or preference. Assuming the latter, try
these things in this order:
1. Hit the Reset button in Vectorworks Preferences (Tools
menu/Options). Try running Vw for a while to see if that has fixed
it. If not...
2. Go to Vectorworks Preferences, click the User Folders tab, then
click the Explore button in the top right of the dialogue. This will
reveal the user folder. With this folder still open, return to Vw and
quit. Back in the user folder, rename the folder called "Settings" to
"Settings Old" then try running Vw for a while to see if that has
fixed it. If so, you can delete the "Settings Old" folder."