I switched from AVG free to Avast! 8 Free to get familiar with it, so that I can better support my clients who use it. My old Corel PhotoHouse 3 stopped being able to launch. Sometimes it said "encountered an error and had to shut down". Sometimes the error message is "SmartHeap Library Mem_bad_pointer". (The message depends on whether I have certain legacy modes enabled.) I bought Photo House 5, but it has the same problem.
I sent a message the the Avast! support crew, and the tech's help narrowed the problem to the Avast! 8 Free's Behavior Shield.
I was examining the Behavior Shield settings and decided to try adding photohse.exe to Trusted processes by using the Browse. I had to do the two versions individually. Now I can launch either with the shield enabled.
In the Avast! user interface, choose ANTIVIRUS / Behavior Shield / Settings / Trusted processes. The Browse button makes it easy to find the full pathname of the application. Then click Add, and OK.