Disappearing dictionary popup when reading pdf on K3

[zenblu]

Hi,
I have a problem using the popup translation when reading a pdf on my Kindle 3. When I place the cursor in front of the word, the "Begin typing to create a note..." popup shows and immediately another popup begins to show (I'm assuming it's the dictionary popup), but it disappears very quickly and I cannot read it. Once I was able to bring it up somehow by finding a word in document, when it found one, the cursor became slightly smaller and the dictionary was showing properly. I can't reproduce it anymore though.
Is anyone having a similar problem, is it known, are there any fixes?

Thanks!