Thanks to my crash reporter system I have discovered a few people are running into this already. I found the cause of the bug and will have it fixed in 3.4.1. Watch this space for a link to a 3.4.1 beta that fixes it ASAP for those of you who rely heavily on Flickr searching.
Update: I have a fix in place and will release 3.4.1 publicly as soon as possible. In the mean time you can download a beta pre-release of the 3.4.1 with the fix in place: