I have the same card from the same shop and experience similar problems except I don't get crashing apps. Sometimes the phone just has a problem reading the card and if I take it out and put it back in it reads fine. About a month ago it couldn't read it at all and neither could my PC. I formatted it using SDFormatter and it worked fine again.
A few days ago I saw this thread and checked LOST.DIR. There were 3 files in there but the card was working fine.
This morning the phone couldn't read the card at all. PC can't read it either. Well Windows shows 1 file named DOWN.LOA. When I look at the card using Recuva it says "Unable to read boot sector".
I'm going to try a full format using the phone but I'm thinking I need a different card. I'm a very light user, have less than 2GB on the card, no music. It's not like the card is being written to or read from a lot.