Playback sometimes freezes with capturecard

Hello!
I'm a happy user of Catalyst@macpro with capture card 720x576 2vuy 25 fps 20.7MBps @ CatalystPM 4.40_m329_HD PHX
I have trouble with playback of some files, when capure card input is switched on.
Please, help me solve this bug.
I have some presets. Video input is switched on from menu.
On the concert, when I switch on presets sometimes I loose clips from playback. Sometimes, but not often Catalyst crashes.
I discovered, that I loose avc1 coded clips. When Catalyst didn't crash, I need to switch off Capture card and jump to some presets to activate playback of lost clips.
When capture card is switched off or extracted from MAC - I have no any crash and NO any playback faults.
Thank you so much anyway.

On what drive is your content running? The system disk or an external drive.
You should not run content from the system disk. If you use an external drive for example on FW800 and also a FW800 capture device it might be a bandwith problem...
Hard to tell without the details.

Firstly, m329 is pretty ancient - m364 is generally accepted as the 'official release'. I would use this as a matter of course over m329 any day.

Olli is correct that you should NOT use the system disk for playback.
You do not mention which capture card you use - that's kind of significant.

You should absolutely not use AVC1 encoded footage with Catalyst - this is h264/ MPEG4 content which is totally unsuitable for use with Catalyst. Catalyst works best with codecs that use intraframe compression which use spatial compression only and not interframe compression codecs like MPEG-2, H264, MPEG-4, which use both spatial and temporal compression. Intraframe compression Quicktime codecs are DV, Apple Intermediate Codec, Photo-Jpeg, Animation, ProRes. Although a lot of people still use Apple Intermediate Codec, I personally prefer ProRes - even ProRes Proxy, which is the 'lightest weight' ProRes Codec looks better than AIC, and has better Chroma subsampling and bit depth. It also performs extremely well on modern Mac Pros.

Hugh

Thank you so much for replies.
Catalyst runs from 2 internal HDDs. One of them is ssd 128, another is generic 7200rpm hdd. Both discs are NOT system.
Capture card is blackmagic intensity pro.
MAC Pro OS X 10.6.5
2x2.4GHz Quad-Core Xeon
gpus geforce gt 120 512vram
6Gb 1066Mhz DDR3.

So, I understand my faults:)... In couple of days I will install 364, and will convert avc1 coded clips to right coded. And I feel everything will be fine:)