newly purchased cells from ATCC and they dont grow :-( - (Oct/08/2008 )

Recently we have purchased MC3T3-E1 (mouse preosteoblasts) cells from ATCC. After thawing they seemed OK eventhough they grew little bit slowlier than expected. However after 4 or 5 passages they basically stopped growing.
The test for mycoplasm infection was negative.
In the company we purchased it from they suggested us to use FBS that was NOT heat inactivated and use single antibiotic (penicilin) instead of antibiotics mixture...at first it seemed to help, but again after 2 passages cells virtually stopped growing.
Anyone has any idea whats going on?
I dont have that many experiences with cell culture ...so I am running out of ideas ...
I will be very thankful for any advice

I am not familiar with your cell line, but

I normally follow whatever ATCC tells me to do,
and one time there was actually contamination in the vial that I received, so I camplain to ATCC, and they gave me free replacement.
so I will say call them again and try everything that they tell you to do and if nothing help, then ask them for replacement vail. it might be just a bad vial

What I do fist, when I received and defrost cells from ATCC is check some cells in the microscope adding tripan blue to see % of alive cells. Then, start the culture and left a plate with 2-3 ml of the medium (plus SFB, etc) I used for the culture in the incubator to check if it could be contaminated. if you are having problems with the passages, I would start culturing other cell line who grow in the same condition at the same time to demonstrate I'm not doing something wrong.
In addition, what we do when acquire cells from ATCC is buy in ATCC too a little of everything we need (500 ml of medium, 100 ml of serum, etc), defrost using them, and when we are sure everything is ok, we frost some vials and continue culturing now using our regular mediums (from gipco). This way, they can’t tell you it’s because of your mediums or serums.