Thanks everyone for the very extensive replies, much much appreciated.
I have been doing more testing..
So far I had always experienced this while having the Echoplex receiving midi sync messages from my laptop. I don't seem to be able to replicate the problem when the clock is not running.. exactly same settings but not sending any midi sync messages from the laptop... it seems to never happen.. it might be a coincidence but I'd be surprised since as soon as I turn the clock on again and do a couple of tests it happens again..
My unit is set as follows
MORE LOOpS: 4
Switch Quant: LOOP
not sure what else might be relevant..
ANd all I am doing right now is:
1 - HARD RESET
2 - record loop 1
3 - next loop + overdub > loop 2
4 - over dub something on loop 2
and back to 1..
after 3 times or so.. bam! an old loop appears when switching from loop1 to loop2 (usually after a cycle).
it plays for a bit and then if I let in run couple of times.. it switches to the burst of noise.
So I am not doing anything very particular really. No reverse, no half speed..
What I find especially weird is that this happened even after switching off the unit.. zombie loops?
I am gonna try re-seating the RAM now, as Mark suggested.
@andy: hopefully I will be able to share some of this music soon. I am using the echoplex for a band project with 2 drummers and electronics. Never done this before..