I am using Ubuntu 12.04 on my relatively new laptop. Initial few days, everything worked fine, but then suddenly I started getting a strange problem. After every 2-3 days, the file-system was becoming read-only. I was unable to save/download anything in the installation drive and the system hanged if I attempted to do so, after which I needed to force restart.
I had to run fsck in the repair mode to get it fixed (temporarily). There I used to get the following messages:
"Inodes that were part of a corrupted orphan linked list found. UNEXPECTED INCONSISTENCY: RUN FSCK MANUALLY. fsck /  terminated with status 4. Filesystem has errors: /"
Then it stopped here and I had to restart again, after which it asked whether I want to repair or not, then the system ran properly. After a day or 2, again I used to face exactly the same problem.
The problem become more frequent in the last few days, and even after running the fsck and restarting, was not solving the problem. I re-installed the OS a couple of days back, but even after that, the problem exists. Though it is not that frequent now, but still at times, the file-system becomes read-only and the system stops behaving normally, and I have to run fsck in the repair mode, which makes the whole thing normal.
Yes I keep my laptop switched on for long hours and it does get heated up.