I got the same result on searching "Bla", but searched "ojas", "oja", "bsf" and "Oja" with no issues (they all had a decent number of results). Searched "Bla" again, same error. "bla" also gives me the error.
Searched a string of random letters, got the no results page.
All was done with default search settings (and no "" marks)
The full error has a huge amount of numbers, I'm guessing they might be the post numbers of results or something similar. The numbers are ordered but the order is quite odd, I didn't work it out, but you should be able to reproduce the error by searching Bla or bla.
EDIT: Kay, looks like it's just getting too many results for MyBB to handle. "bla" is of course part of some very common words here on the forum. While "beyblade" doesn't produce the error, "blade" does (it's used in a lot more words).
It's quite odd that you happened to use one of the letter strings that would set it off, blood, haha
That said, a few common three letter strings will set it off; "The" for example.