1. Did a full fresh install, meaning first cwm 5.0.2.7, then cm 7.2 rc1.
2. Installed then gapps.
3. Installed s2e, set it to mount as ext4, reboot.
4. checked dalvik, apps and download cache on sd in s2e. reboot.
5. tried to download apps from market, every download failed.
6. tried to clear cache from market. no result.
7. cleared dalvik cache. still nothing better.
8. resisted the urge to throw my gio to the wall.
9. see 1.
10. gapps again
11. installation of apps works just fine without s2e
conclusion: stay away from s2e, or try dt a2sd again - sometimes.
BTW: my sd-ext partition was formatted by cwm, checked on pc as fully functional ext4.