Edit: Yay!!! I seem to have fixed the problem. I reformatted my hard drive, and installed a different copy of windows i got through a student program. I had previously been using the acer copy of windows. Anyway, it's either the copy of windows I was using had some tweaks my firebox didn't like, or it has less bloatware and freed up just the right amount of ram. I do still get interruptions when opening programs while playing music, but I've got a 1gb stick of ram coming this week, and see if that totally clears the problem up. If thats the case, listen up firebox users... you *need* more than 512mb for reliable use.
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I've definitly had similar problems. I have a few posts on here and hydrogenaudio trying to fix the problem. However, consider yourself lucky by being able to fix it with a restart. Mine stutters intermittently no matter what I do. It records fine, but the playback (ie not direct monitoring) makes it impossible to overdubb, and makes it so I can't use it as my laptops sound card to just listen to music.
What type of computer do you have?
My specs are:
Acer laptop
3000+ semperon
512mb ram (getting 1gb stick in a couple days, will let ppl know if this fixes the prob)
TI cardbus chipset
Tried a VIA and ....(cant remember the other brand, but not TI) firewire card
SiS internal graphics
4200rpm internal harddrive
I've gone through an insane amount of troubleshooting, but have come up dry. Maybe I can gleen some info from your setup as you're the only other person I've heard a similar problem from.
Thanks