With ThinkPad X220 and 240 GB Intel 520 SSD I also get serious filesystem corruption errors running Ubuntu 12.04 desktop. "Serious" means: just now I couldn't boot from the Ubuntu partition on the SSD; I had to boot from another disk and fsck the Ubuntu partition on the SSD, and even then the booted Ubuntu 12.04 system behaves erratically, indicating file corruption has occurred.
Until I figure out what is going on I have gone back to running Ubuntu 11.10 from my trusty old Hitachi hard disk.
With ThinkPad X220 and 240 GB Intel 520 SSD I also get serious filesystem corruption errors running Ubuntu 12.04 desktop. "Serious" means: just now I couldn't boot from the Ubuntu partition on the SSD; I had to boot from another disk and fsck the Ubuntu partition on the SSD, and even then the booted Ubuntu 12.04 system behaves erratically, indicating file corruption has occurred.
Until I figure out what is going on I have gone back to running Ubuntu 11.10 from my trusty old Hitachi hard disk.