i first heard about the known bug called "random panning", which you've been experiencing, here at:
http://www.basscadets.co.uk/emu/
basically, i understand that this has been a problem with about every version of EOS and is tied to the RFX card, meaning no RFX card, no problem. the problem we have, fellow E4 users, is that EMU is going to software next year, and as far as i understand have pretty well dropped development of a new EOS version and pretty well don't give a damn about their old hardware stuff anymore, in fact, i understand that's why 4.7 was never fully released, they cut QA tests on it before it was fully bug free and re-routed their focus to their new software...sucks for us, huh?
we need to make sure them motherfuckers at EMU keep supporting our E4's including fixing bugs like this one! Let's ALL write EMU an email today, fuck that, let's call!
here's the excerpt:
RFX32 Important information
The RFX card is EMU's effects addon for the sampler. Great feature list with effect plugins etc.
I must warn you though that since it came out it has suffered from one huge defect.
This defect is known as "random panning" and it occurs when you play samples that have a fast attack such as percussive/drum style samples. When played you will hear the sample bounce from left to right randomly on each hit, and it doesn't matter which EOS version you use.
As you can imagine this bug makes the rather expensive RFX addon and therefor the sampler unusable in a recording.
EMU can fix this in EOS, but up til now haven't.
The bug is in the RFX driver. Once RFX is installed all audio is routed through it first so everything is affected - not just effects.
I urge you to pester EMU about this EMU.Support@customercare.creative.com and to think twice about buying the card or anything RFX related (ADAT) until its resolved.