I have the pay version of DTG and only have a couple of simple spreadsheets, however whenever I tried to search for text within them the sheet closed and I was left with the Splashscreen again.
On trying to open the document again I got the message that the previous document hadn't closed properly and did I want to recover any changes?
It didn't matter whether I answered Yes;No or Cancel, the same thing happened when I tried to search again.
I reported the error to Dataviz who asked me to try with other databases but I got the same result.
In the end I found that my problem could be solved by changing from the default Android keyboard to the Touchpal one.
So I don't know whether this is only an issue for me, or users with the same phone (Samsung Galaxy 1.5 running GalaxoHero 1.1 rom), but if anyone else has the same issue, try changing keyboards.