What happens when you open a Terminal and then
cd /Applications (if that's where you installed it)
cd Toast 8 Titanium
open ./Toast Titanium.app
This way, you might actually get an error message in the Terminal about what's going wrong.
In worst case, try uninstalling Parallels via their uninstall utility (it's in the installation disk image) and reboot, then launch Toast 8 again.
It also won't hurt to install the latest Toast 8 update, if you haven't installed it already.
There's a chance that Parallels' and Toast's drivers have a conflict. You should only use the most recent versions of both products.
cd /Applications (if that's where you installed it)
cd Toast 8 Titanium
open ./Toast Titanium.app
This way, you might actually get an error message in the Terminal about what's going wrong.
In worst case, try uninstalling Parallels via their uninstall utility (it's in the installation disk image) and reboot, then launch Toast 8 again.
It also won't hurt to install the latest Toast 8 update, if you haven't installed it already.
There's a chance that Parallels' and Toast's drivers have a conflict. You should only use the most recent versions of both products.