''It shouldn't be a shock that the romance between Penny [Kaley Cuoco] and Leonard [Johnny Galecki] will be dysfunctional and not go far,'' says exec producer Chuck Lorre of Big Bang's beauty-and-the-geek relationship. Perhaps that's because guest star Sara Gilbert will join the cast as a love interest for Leonard. Lorre says this season's stories will be ''emblematic of who these characters are, like Sheldon's [Jim Parsons] inability to deal with things that we take for granted. Something as simple as someone saying 'Can you keep a secret?' It torments Sheldon because that's not the way his mind works.''