[Farstrider]

I have similar problems. Paging down almost always works perfectly. But paging up causes an immediate crash. So I do the following dance:
Press home
Launch Mobi
Press home again
Launch Mobi again
This works, even though it never actually ends the program. But I always find myself about 20 pages back from where I started.

But search in Mobi never ever works. I keep a copy of ereader on my TP for searches, and a copy of Mobi for actual reading, because I like to read in full screen and ereader will not do full screen. Kind of ridiculous really.