Version:           3.1.94 (using KDE KDE 3.1.94)
Installed from:    Slackware Packages

Replication is not always consistent but I'd say at least 85% of the time:

Google for something (I use the gg: shortcut but anything really works)

When you get the Google results, scroll down to the bottom of the page where the second search box is.  Highlight the text -- sometimes you can just overwrite it by typing (correct operation) but a lot of the time the text will be highlighted, the cursor will be blinking in the text box, but you won't be able to type or move the cursor unless you click in the text box again (and lose your selection).

It seems to help if the mouse does not move out of the text box area, but this doesn't seem to be the cause of the problem, nor does left-to-right or right-to-left selection  of the text seem to give any advantage.