Keyboard Appears To Repeat Strokes?

For some time I have noticed that, when completing dialogue boxes, it would look as if a key had stuck and that letter/symbol would start to run across the box like this until I hit another key. This happened randomly and with different keys. I tried altering repeat rates etc but it made no difference.

Assuming it was the, wired, Microsoft Comfort keyboard I splashed out and bought a new Micosoft Arc wireless keyboard a month ago. Expensive but a lovely keyboard however, you guessed, the same problem!

Out of interest I wrote to Microsoft for help. They sent me a new keyboard and told me to throw the old one away!