I am not an expert but have you given the bobbin area a good cleaning out? Sometimes fuzzies can affect machine operation.
Colleen

Cross stitch is dense so you may have to add some more stabilizer on top or underneath or adjust the tension a bit tighter. If you are using fleece, try using a ball point needle and cut-away stabilizer.

Since you have the scraps, I would do some test runs to make sure you have the best combination before ruining more good fabric.

It could well be the design has not been well digitised. There may be a part that is wa too dense. Try a design that you know stitches out well. On fleece, I use WSS on both sides and have had no problems.
Ahhprods, my 300E loves the Mettler poly threads.

I have a 300E and have had several problems as you described. It seems that if I just wait until the next day they will stitch. I think there may be better embroidery machines out there. My Husband bought this for me last Christmas and bought a Janome bacuse I have a Janome 4800 and Absolutley LOVE LOVE LOVE it.

As far as the best thread. I have tried it all. Mine seems to have a problem with breaking the thread. I have just leaned that I will probable have to stop and start several times to get a design done.

I am in agreement that you should use a heavy washable stabalizer on both sides. I do this on my towels and it seems to help.

Lynne

I don't have any of these problems with my 300E. Perhaps you're using a bad type of needle. I use a Schmetz universal for EVERYTHING and don't have thread breaks, tangles, messes etc. I use Maderia rayon or Mettler poly and sometimes cheapy threads from the internet.
Are you keeping the bobbin area clean? It is an excellent machine.