This is a weird one! I was in the process of laying down a guide drum track and was using the patterns contained in SSD2. I dragged and dropped some patterns into X2's sequencer with no problems until I tried a "Variation 4". It would not let me grab it!
I tried various other #4 patterns and none of them are selectable.
I closed X2 and opened Toontrack Solo and had the exact same problem. 
Has my computer gone insane?
 
Grum. 
 
Solution:
 
I did a bit of scouting around and it appears to be an Admin thing. Running Sonar (or Solo) as admin cures the problem.
Freaky.