ITunes For Mac :: Can't Access Store - Comes Up With Unknown Errors

I'm trying to run iTunes Match and it simply stalls at stage 1. Yes, I believe I've tried the fixes listed in other places where this seems to have been an ongoing issue since launch - and not all of these work for the people there, either. These include removing stoping and starting Match, stopping and starting Genius, stopping and starting Genius and Match, moving the iTunes Library files and reimporting them as new libraries and so on. Nothing is working for me. 

I run iTunes match and it matches "most" of my songs and then stalls. I've left it for days to see how long the stall is and it never clears.Over the last few days' stops and starts, it's matched as follows:

13508 / 14010
13535 / 14010
13541 / 14010
13998 / 14010

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iTunes frequently also can't access the iTunes Store or comes up with unknown errors.this is an entirely new music library. I set up my Mac from scratch a few months ago with a new SSD. My music library had a lot of old files sampled at low bit rates - I was re-ripping to flac for my hifi, so I decided to re-rip to iTunes as well at the same time (my previous iTunes Match had lots of stuff it couldn't match, but was uploaded at a low bit rate since that was all that was available). My network connection is wired and I have very good broadband (cable) speed.