In that case technically you're posting in the wrong area - this one is for the standalone version of SmoothEdit (i.e. v1.0.8) not the one built into Myriad (i.e. v3.0.25 etc.) Have a look and see what Mia driver version you are running, and also make sure it's running in WDM mode not Purewave mode - this can cause the problem you are seeing. You can see details on how to do this via http://forum.psquared.net/Topic212-9-1.aspx
If you're still having trouble let us know what's the exact version of the Mia driver and what OS you are running on. The ideal one for older Mia's is 6.0.8 or 6.0.13, but if you are on an almost new one then you may be better going for 7.02 or 7.03