Insert Edit Problems

Our system:
FCP 6.0.4 on Mac OSX 10.5.4 w/ 2 x 2.8 ghz quad core intel xeon
Media storage is on a Terrablock
We're using Blackmagic I/O's (v6.7) and Blackmagic videohub router
Quicktime 7.5
Digibetas (500 and 2000)

Here's another lovely FCP issue: Insert editing doesn't seem to work very well. We've been having an issue with starting an insert edit (a SD project, sequence is pro res 422) and one of a number of problems will crop up: 1, there is no video, just black in the edit to tape window. 2, the correct frame shows up as the deck is pre-rollng but stays frozen after the edit point so you get a freeze frame on tape, 3, you get an error message that the duration is only 1 frame (even though there is both a valid in and out point on the timeline and in the tape machine window) and it won't make the edit, and, last but not least, the machine just cues up to a different in point than what is entered.

#1 above happens the most, the rest are sporadic but do occur.

The sequences are graphic heavy and of a longer format (9-13 minutes) that we sometimes need to make a quick fix. When the edit doesn't work and you waste a lot of time on this, it gets maddening. We've been troubleshooting this for weeks and is doesn't happen all the time. What we have found, however is that you cannot make an insert edit if there is any type of video or audio transition. But the problem still occurs sometimes even when you avoid transitions with your in and out points. Anyone out there have this problem, heard of it or have any other solution ideas?