@ luchiolb maybe you should try this! back to start, Re-flash Floyo-0.15 ROM and update.zip but before you Re-flash Floyo-0.15
do this
2) SD card should be formated 1 partition - FAT32 - no name
(note: i use MiniTool Partition Wizard Professional Edition for this)(<unmount><re-formated> by Xperia X8 under <settings> for stock android folders created in SD card i.e. <Android><.android_secure><DCIM><LOST.DIR> folders must be present in SD card - create sd/xRecovery/backup folders
3) Switch off <USB Debugging> when copying files to SD Card
4) Re-flash Floyo-0.15 ROM and update.zip
5) setup SD card settings under <CyanogenMod settings> to <enable> Apps2SD+Link2SD compatibility
and this
To use the APP2SD function...
go to <settings><CyanogenMod settings><Application> select <Allow application moving>
go to <settings><CyanogenMod settings><Application><Install location><automatic>
this what i did and it works i can now install apps and move my new installed to SD card