I've been using an IOBlix since it was released with zero problems. Actually, one of the best purchases I've made. Make sure your using the latest drivers (Aminet) and if that doesn't help and it's definately a hardware problem, check with Software Hut, because I know they were doing the upgrade on them. They might be able to help you out.
It's a good card. I've had no problems in nearly four+ years.
My system is a A1200T Micronik Zorro II, Blizzard 060. Can you give us some details on your system?
IKE