I did just two tests from chess mentor and it hiked my rating from 1400+ to over 1700!

Could you please tell me how do I interpret this new rating?  I wouldn't want to reach Grandmaster level too prematurely!   

on your topic i wonder can my rating goes down when dealing with c.mentor?

Chess Mentor ratings seem wildly inflated to me.  I'm up to 1915 after less than a week of training and I'm barely a mid 1400's player.  Have a feeling the course was designed that way to encourage use.  Not meant in any way to disparage the Chess Mentor experience which is wonderful, although it has the potential to be addictive.  I can't believe how much ground I've covered already.  The whole Chess.com site is great!

Chess Mentor ratings are inflated but that's not very important, what is important is the learning effect. Losing points on CM is possible but rare; if you want to lose points do Silman's lessons.

It is easy to lose points. Get one lesson wrong and lose 80 or 90 points. Then spend a week getting all those points back one at a time. It gets harder and at times more frustrating the longer you have been at it and the higher your rating gets. I've put in about 130 hours over the past 5 months and am over half way done with all the courses. 

Just pretend that your Chess Mentor's rating is your chess potential if you do your best and train regularly