I have similar problems with Poser 4.0.3 and the Pro pack. After working with either for so long, Poser just locks up, and sometimes locks my PC up as well. I talked to Tech Support today about it. I was using Norton CrashGuard, but I removed it since Tech Support said that it could be causing the problem. I am still having problems. I was told by Tech Support that this is a rare problem. They will not know about problems unless they are informed. Give them a call at (831)462-8902. This is the direct line to tech support. I plan on working with them until I get my problems solved.