Integer to Floating conversion error

I get strange behaviour with integer conversion; in the following example T4Frozen never reaches the value 790 because it turn back to 700 when it step over 767. This happen both on the target and on Dscope.

 T4Frozen=700;
 while(TRUE){
   PeriodoEncoder=(float)T4Frozen;
   PeriodoEncoder/=2.5;
   T4Frozen++;
   if(T4Frozen>790){
     Dummy=700;
   }
 }