Well, while I don't fully understand the specifics of it... those older versions of a2sd do come with a warning that seems to be left out most of the time:
[SCRIPTS]CronMod-INT2EXT (updated 02/28) - xda-developers
Which would seem to imply to me that at 959 MB on sd-ext you are well beyond capacity...
If you feel like taking things apart and trying again from a clean build... I've been using (slightly modified) versions of obijohn's int2ext script for awhile, and managed to get some pretty heavily loaded test setups (I got up to around ~1.4GB on my 2GB sd-ext at one point iirc) - but I was using the plus version and manually linking several of my cache folders to keep my data partition from overflowing with cache too so... your mileage may vary, I suppose?
Also if you want to use obijohn's scripts you need a working rsync binary - JBC/PAC includes one, but for most other roms you'll want a statically compiled one... I've been using this one:
rsync your Android [asksven]
(only binary I could find that actually runs properly on my phone, newer static binaries from debian site fail to run for me)