=== modified file 'addons/openerp/validators.py'
--- addons/openerp/validators.py	2011-01-17 11:57:11 +0000
+++ addons/openerp/validators.py	2012-01-05 18:35:24 +0000
@@ -81,10 +81,16 @@
 
     def _from_python(self, value, state):
         val = value or 0.0
-        t = '%02d:%02d' % (math.floor(abs(val)),round(abs(val)%1+0.01,2) * 60)
+        hours = math.floor(abs(float_val))
+        mins = abs(float_val) - hours
+        mins = round(mins * 60)
+        if mins >= 60.0:
+            hours = hours + 1
+            mins = 0.0        
+        float_time = '%02d:%02d' % (hours,mins)
         if val < 0:
-            t = '-' + t
-        return t
+            float_time = '-' + float_time
+        return float_time
 
     def _to_python(self, value, state):
         try:

=== modified file 'addons/openerp/widgets/listgrid.py'
--- addons/openerp/widgets/listgrid.py	2011-09-28 10:35:28 +0000
+++ addons/openerp/widgets/listgrid.py	2012-01-05 18:36:33 +0000
@@ -526,8 +526,13 @@
 
     def get_text(self):
         val = self.value or 0.0
-        t = '%02d:%02d' % (math.floor(abs(val)),round(abs(val)%1+0.01,2) * 60)
-        
+        hours = math.floor(abs(val))
+        mins = abs(val) - hours
+        mins = round(mins * 60)
+        if mins >= 60.0:
+            hours = hours + 1
+            mins = 0.0        
+        t = '%02d:%02d' % (hours,mins)
         hour, min = t.split(':')
         if int(min) == 60:
             t = str(int(hour) + 1) + ":00"