Thanks for the attaching the file. There definitely is an issue here, a couple of things are going on here. Any time a command that requires looking up the word at cursor gets executed its going to fail on a line like that. Paren matching, double-click which does a select-whole-word command), or Find with the option to initialize with the word at cursor are all going to fail. All these commands use the reg-ex search engine to do their work, and they should fail silently, only it's not in this case with a really large string of characters like that. It needs to have to be fixed, but this is not a hotfixable item. I'm filing a report and should hopefully be addressed in the next release.
The only thing I can recommend is to temporarily disable the paren-matching code (Tools > Options > General... > More > Highlight matching blocks) and try to avoid double-clicking on the line or calling select-whole-word.
