I have some news. The short story: Erased partition table; restored backup of faulty reader; restored mmcblk2p1,2,6,7,8,9,10 of the good Reader to the old one. Now everything seems to be working fine after leaving on sleep for 7 hours and using it to read for 1 hour at three different times. Used the browser too without any problems.
Will test for a longer period of time without doing further changes.
I've been using heavily (several hours a day) my previously faulty PRS-T1 and can confirm that the problem is solved (hoping it does not come back again). I read from several books in different languages, changing dictionaries every time, added annotations, browsed several websites, downloaded ebooks and a couple of wallpapers without a single problem.
I read somewhere on the Sony forums that one used said that repartitioning solved his dictionary problems. I'm the second user who's reporting it as well. I didn't change the partition sizes but rewritten the partition table of the unit and this seems to have resolved the problem, wherever it was.
I will post a detailed step-by-step procedure for the benefit of others having the same problem.
Last edited by entodoays; 02-02-2013 at 11:31 AM.
Reason: Added more info