B visa with multiple entries

[monica2004]

Last year I received a B visa with multiple entries of 1 year duration(expires in 2004 june 23). I already been 5 times to usa since then.Almost everytime I got the I-94 for 5-6 months(but never used it full), this would be my 6th entry but I'm afraid of having problems because of too many entries and such a short stay in my country the last months.I'm a prospective student.I already been accepted to one university but I dont have the student visa yet.
Does anyone know anything ?..Is there a problem if I visit usa again? Is there any limite on the number of entries or the time spent in 1 yr in usa by a B visa holder.
Thank you !