First question would be are you still using the dual floor (pressurised) baskets, if so, ditch these ASAP and get the non pressurised baskets. I think the Krups basket referred to in the Ikon Summary thread fit your machine.
Once you have the new basket, then its time to work on dose / tamp technique.
Dose sufficient coffee into the basket so that once tamped (no more than 10 - 15kgs of pressure on the tamp), when you put the portafilter into the group head, you can pull it out again (before running a shot) and the top of the coffee has a slight (very faint) impression of the shower screen (or screw if it protrudes from the shower screen) but the puck is not broken / damaged.
Once you have those two things (single wall basket and consistent dose / tamp), then you can work on grind. The advise you received (to grind finer) was in itself correct, but of only limited use without the above two things sussed first.
The dual wall filters (crema enhancing) artificially create the pressure required to extract a "good" coffee and make it difficult to achieve a good consistent pour and can result in watery / bitter tasting coffee.