FLUENT Version Mis-Match Discrepancy

asd

Hi, i updated my fluent verson from 6.2 - to 6.3 and when i execute the journal file as prepared from the older version on the newer, i obtain an error for one case study in the form of:

reversed flow in 53 faces on pressure-outlet divergence detected in AMG Solver: temperature

My jounral file works for all cases (meshes) in both the older and newer version and i obtain same results across the two versions, thus indicating the UDFs are OK. HOWEVER, i had prepared a finer mesh, which happens to crash on the newer version with the errors as above, yet is operable on the older through the jounral file prepared earlier!!! the fact that my journal file prodcues the same results on both the versions for coarse meshes, yet crashes only on the newer version for the finer mesh is a source of great confusion. I cannot understand this discrepancy!!! It seems to be a strange error. Any suggestions would be greatly appreciated.