Help regarding F1 student filing I-140/I-485

Only a few days left for the crazy July. Like many others, I am also prepare the I-140/I-485 application.
I am currently a F-1 student and going to graduate in the end of this year. My friend told me that I should be cautious about I-485 application because after filing my I-485, I will not be allowed to apply for H-1B as F1 (or H-1B application will be rejected frequently).
Does anyone have any information on this issue? Appreciate your help a lot!