I have an ME-50B I've been using for years, and it's honestly one of the best bits of gear I've ever used or had.
Although it's never been bad on its own, since I've been using 'better' gear (better pedals and upgraded to a GK rig) I found that it seems to 'react' with other gear. My guess is that it's the compressor too, I've had a bit of trouble with that bit.
As soon as I introduce any pedals after it, like distortion or modulation it just doesn't work. My guess for a while now is that it's been the compressor settings. I use it on the D-Comp setting, which is a Dyna Comp model, and while I love its effect on my tone (actually struggling to replace it) it just kicks off like mad and produces silly feedback with my amp. Just seems to be giving out a real hot signal with the comp on and anything that is even remotely high gain or responds to gain afterwards just clips and sounds a bit crap.
Try mucking about with the comp settings or just turning it off completely, see what happens. If anything is really high gain in your signal path, try taking it out and see what happens.
Ibanez ATK 300/400 //Lakland 44-01 //Ibanez Musician
MXR //ZVEX //EHX //Boss //TC //Aguilar //Hardwire
Gallien Krueger 700 RB // 210 RBH