I have been having this exact problem for quite a while, and even started a thread on it
here last month. I ended up letting my eqclient.ini recreate itself and that fixed my problem, but only for a very short time. A month later, it's as bad as it was when I made my post.
Several of the suggestions in that thread involve sound or insufficient hardware, but that is definitely not my issue. I don't have the beefiest machine out there, but it's an Athlon 2000, 1gig RAM, 7200 RPM drive, Radeon 9800 pro - it's not struggling to play EQ. Your suggestion that this is a problem with INI file writing is intriguing to me, and would help explain why a fresh INI file might reduce the problem for a short time. I'm very curious to see where this discussion goes.