I've never seen that error before. Some quick looking shows the error occurs any place the silk screen layer intersects holes (i.e., pads) in the soldermask. This isn't a problem for making a successful board, as issues like this get taken care of in the process - you'll never see silkscreen across a pad, but it will affect how the board looks - Read an important comment below.
This illustration shows one of the errors.
One this to note in this illustration - the blue cross-hatching is the Tstop layer. "Fixing" these errors is pretty simple. Don't display the Tstop and Bstop layers. This is why I've never seen it before. The illustration below shows the same area with the Tstop layer turned off - no more errors.
One real problem I did notice - all of your fonts are "proportional" - proportional fonts
do not reproduce properly in Gerber files. Typically, they are too long and don't show up as expected. Change any labels that will be on the silkscreen to Vector - then
what-you-see-is-what-you-get. You can do this easily by grouping everything, and changing font properties all at once.
Hmmm... maybe this has been fixed in version 7. The picture below is the board as it looks in Eagle. The second is the Gerber silkscreen layer.