Win CS5.5 RAMpreview audio troubles

Question

Hi
Hopefully this isn't covered somewhere.  I had a bit of a dig, but I couldn't figure any clear search terms and so on.
It's sort of a bug question, sort of a request for advice.
I''ve got this fairly large project I just moved over from AE7 (!) on a different machine.
I used RAMpreview to check the edit and audio sync periodically, as you do, and it was slow but fine.  I tried the same thing in CS5.5 and it had what my mum would call a pink fit.  Sometimes even crashing.  Mostly it would grind away for minutes on end, indicating only 'Background Process Status: Loading Projects...", before it even started rendering the frames.  Then the preview would seem very confused about which frames it had rendered (green and blue frame cache indicators jumping around and disappearing altogether), the playback would be choppy if at all and the whole program becomes slow-to-unresponsive.
By the way, Previewing is fine.  It's only RAM preview with audio that this happens.
The first thing is, turning off multi frame rendering solves the problem and restores the RAMpreview functionality I know and love.  So that's cool.  But I'm still curious as to what's going wrong. I have checked the memory settings guides and reducing the number of cores to use down to two (Quad core Intel i5 system) and adjusting the RAM balance did have an effect.  But the long cruching before rendering and the halting unresponsiveness was still present to some degree.  No multiframe at all is still the most reliable by far.
Secondly, the size of the project is probably important.  This is a big, messy project. 1080 with lots of media, lots of effects, many nested comps. I just did a much simpler project that had audio synching without any hassles using all four cores (which I'm probably better off not doing, but it worked is the thing).  So it's just this project that the problem has appeared in so far.
Is there anything I can or should do about it, some box I haven't ticked somewhere perhaps?
If there's no particular fix, working with multi-frame switched off and then switching it back on for full rendering seems like the thing to do.  Would you agree?
My system is an Intel i5 quad core, running Windows 7 premium with 8gb
thanks

Answer 1

Sorry about the delay.
Todd:  Yes, disabling the audio (using those two core settings I mentioned) makes it actually start rendering a lot quicker (and the rendering is noticeably faster with multiframe switched on).  There is a still a period where the program seems to halt while multiframe rendering, I assume, boots itself up.  But I suppose that's normal.  RAMpreview rendering with multiframe switched off begins almost instantly, but it wouldn't have to do any special reorganisation of data in that instance I guess.
When it did manage to render in multiframe with the sound on, the sound and the picture were often jittery and out of synch.  It does seem to be the audio it's having trouble with, yes.
If it's a known problem then I guess it can't be helped much.
Mylenium: Hmm.  I'm not sure I read you right, but for the sake of it I'll say there aren't any effects on this audio track.  The project audio settings are the same as the file itself so it shouldn't be being resampled.  A decent amount of my footage does still have embedded audio but it should be switched off and all the layers in the master timeline have their audio switched off, so hopefully it's being ignored even if any is on by mistake.  That may not be how it works however.
My recent smaller project used pretty much the same working set up and didn't have the same problems.  So I think if it was doing the same things at that point, the smaller project footprint meant it didn't hurt RAMpreviewing as much.  Unfortunately I don't have an intermediate sized project to test with at the moment.