Q1. What version of Inventor?
Q2. What Service Pack or Update?
Q3. What OS? (3b - is this Win on Mac)
Q4. What graphics card and driver?
Q5. What setting on Tools>Application Options>Hardware tab?
Q6. Can you attach image showing this behavior?
Q7. Can you attach sample *.ipt file showing this behavior?
Q8. Have you rebooted the computer and this behavior persists in any new file?
Q9. If you open an existing file - can you see the sketch lines when editing an existing sketch.
Q10. Can you create a Screencast recording of the steps you are using that demonstrate this behavior?
Q11. Is there a logical reason you didn't supply any of the information from Q1-10 in your original post?
JDMather wrote:Q11. Is there a logical reason you didn't supply any of the information from Q1-10 in your original post?
Because it's your responsibility to figure out what on Earth the poster is talking about.
Rather slim @JDMather you are getting sloppy, I am sure you can think of at least a dozen more questions to ask.