problem using LADSPA

I am running the 2.1 64bit version I have freezing problem as soon as I am using LASPA effects wether in Ardour or in Jack rack..most of the time, this ending with a watchdog message.. This problems never occur while playing but at the end, when I press stop. This problems are systematic : basically I cannot create music using the LADSPA effect.. As I am newbie in Linux Mao, I only tested for the moment with the CAPS effect, as I am interisting in the Amp and Cainet effect I have checked up I have no IRQ conflicts : # cat /proc/interrupts CPU0 0: 215 IO-APIC-edge timer 1: 103 IO-APIC-edge i8042 7: 0 IO-APIC-edge parport0 8: 0 IO-APIC-edge rtc 9: 0 IO-APIC-fasteoi acpi 10: 0 IO-APIC-edge MPU401 UART 14: 9114 IO-APIC-edge ide0 15: 876 IO-APIC-edge ide1 16: 3 IO-APIC-fasteoi ohci1394 17: 0 IO-APIC-fasteoi Mia 18: 11564 IO-APIC-fasteoi nvidia 19: 0 IO-APIC-fasteoi libata 20: 0 IO-APIC-fasteoi libata 21: 8980 IO-APIC-fasteoi eth2 22: 2 IO-APIC-fasteoi ehci_hcd:usb2 23: 1708 IO-APIC-fasteoi ohci_hcd:usb1, libata NMI: 0 LOC: 110761 ERR: 0 my latency seems good as well : # lspci -v 05:07.0 Multimedia controller: Motorola DSP56361 Digital Signal Processor (rev 01) Subsystem: Echo Digital Audio Corporation Mia rev.1 Flags: bus master, medium devsel, latency 192, IRQ 17 Memory at d1000000 (32-bit, non-prefetchable) [size=1M] so what to do, I have tried the "soft mode" in jack, it did not changed anything..