Unlikely its directly due to Poser as hardware lock ups should be too low level for applications to cause but it could be due to a thirdy party component Poser makes use of.

Its always worth checking for the latest video drivers even if its a new card.

Would also check Flash and AIR versions are up to date as you are using 64Bit.

If you don't already have one, I would suggest create a system recovery disk (Control Panel->System and Security->Backup and Restore - "Create a system repair disk") just in case powering off the PC has damaged something on the disk.