Parallels won't launch at all

I have a new iMac with Leopard and OS 10.5.2 with 2 Ghtz processor and 2 GB memory. The Apple Store installs Parallels Desktop 3.0 for Mac for me. I installed Windows XP Professional and then QUickbooks and Quicken. It all worked for a while though the Parallels would sometimes start only if it was reset and relaunched. Now it won't work at all. What should I do?

 

Same here

Was working fine, now tells me my .hdd is in use by another application.