Since we don't know your computer specs, we can't speculate on why you're having problems.
I'm sure the developers at Cakewalk do their best to make Sonar as stable as possible, but there are so many hardware platforms out there (motherboards, CPUs (Intel, AMD)), desktops, laptops, memory (DDR, DDR2, DDR3), soundcards (built-in, PC Card, USB, Firewire, serial, S/PDIF), operating systems (Windows XP, Win 7 and Win 8 plus Windows running on MACs) and plug-ins (many of which are homegrown), its impossible to make an application that 100% stable with all these different variables. Cakewalk does publish a list of minimum requirements to run Sonar, but that doesn't stop people from trying to run it on lesser equipped computers. Yet whenever someone has a problem or a crash, they first blame Sonar. Maybe they should be looking a little harder at their equipment, other software running, plug-ins, and Sonar configuration to find an answer. More often than not that's the culprit. I'm not saying to say Sonar is perfect, but no one should be crashing all the time because of Sonar.