Editing one hour show with XDCAM EX 1080/60i HQ VBR video on Pro Res HQ timeline.
Machine is Mac pro Dual quad core 2.3 GHZ, 10 GB ram, FCP 7.0., Newest QT and pro app, & Kona III card. Video drive is Apple Xserve raid, tested with Kona speed test at write 340.2 MB/s, read 282.3 MB/S
This is the second of 5 one hour shows and I'm going crazy with crashes. Everything stays pretty stable for the first 15-20 minutes of the show on the timeline, but now at about 20 minutes in I'm getting crashes every 10-20 minutes.
The first show I tried editing on a DVCPROHD timeline because that's the final delivery to HDNET. That show was a nightmare so I figured I'd try using a proRes HQ timeline instead then convert at the end. Running into the same problems and I've edited 2 dozen one hour shows using the ProRes timeline with no problems.
The one thing I've done that is different is use the Coremelt plugin for luma levels and a few sky replace shots (I'm color correcting as I go either with the Coremelt plugin for luma or the FCP 3 way color corrector).
I'm also getting a lot of "out of memory" warnings when I try to render which requires a restart of FCP and it seems to go fine.
I tried setting up a new user, trashing preferences and I don't really have time to reformat my system drive and reinstall FCP, at least at this moment.
Producer/DP, HD series, "Discoveries...America", "Discoveries...Ireland", "Discoveries...Spain",
"Discoveries...Argentina", Discoveries...India", "Discoveries...Asia", "Discoveries...Africa"
Several people have been reporting crashes with XDCAM EX, but the other issues you're having with DVCProHD and ProRes HQ point to something more sinister with your computer, as they are both fairly easy codecs to deal with, requiring no extraordinary hardware.
BTW, going to ProRes HQ is overkill. ProRes 422 is more than adequate and the non-HQ version of the codec has fewer problems for most people too.