Equation loses text when clip art inserted

[randall]

I like equation in word 2007 but if I insert clipart all the characters in
the equation disappear.

I have tried sending the clipart behind the text and also "send to back" to
no effect.

The clip art is formatted "behind text" and everything is fine on the screen
and in print preview but when I print the characters in the equation have
gone - all I get is the horizontal line!

Advice please!