I have 2 cards both Nvidia, 1 tnt, 1 Geforce, and have no problems. It seems to me the problems were due to drivers not being updated. Sounds like you may be refering to the activation issue - by making the system think it is a new system, it requires reactivation.
I run Qcharts 4.1, with no problems; however the new beta 4.2, I have had a couple of program errors and shutdown, but none today. I run 3 windows of Qcharts, 2 of 4.1 and 1 of 4.2.