When driving my 2004 LLY D/A CC SB this afternoon, the speedometer locked up at around 27-28 mph a couple of times. I know that I was going faster (probably 45-50) each time. When I slowed down to a stop, the speedometer seemed to work properly as my speed slowed through where it had locked. All other guages worked fine (or appeared to, anyway).

Any ideas?

Thanks for your help!

Most likely a sticky gage. You will probably need your instrument cluster changed.