I use PowerDVD 11 and seem to have not Blue-Ray problems. A new version might have a bug, any updates to the software? Windows 7 doesn't do Blue-Ray, so I might have to narrow the problem to PowerDVD or some codec it installs.
Any chance the DVD player you are using is causing the problem? Any updates for it, such as firmware?
Do all Blue-Ray discs have the same problem? I don't suppose Digital Rights Management is involved since you are in Australia?
Ever thought of getting more memory?