diff --git a/LaserGRBL/AssemblyInfo.cs b/LaserGRBL/AssemblyInfo.cs
index 1bb6a01a..8e9f2b36 100644
--- a/LaserGRBL/AssemblyInfo.cs
+++ b/LaserGRBL/AssemblyInfo.cs
@@ -31,5 +31,5 @@
 // È possibile specificare tutti i valori oppure impostare valori predefiniti per i numeri relativi alla revisione e alla build 
 // utilizzando l'asterisco (*) come descritto di seguito:
 // [assembly: AssemblyVersion("1.0.*")]
-[assembly: AssemblyVersion ("5.4.0")]
+[assembly: AssemblyVersion ("5.5.0")]
 [assembly: NeutralResourcesLanguage("en")]
diff --git a/LaserGRBL/Core/GrblCore.cs b/LaserGRBL/Core/GrblCore.cs
index acf46098..140581f3 100644
--- a/LaserGRBL/Core/GrblCore.cs
+++ b/LaserGRBL/Core/GrblCore.cs
@@ -3851,12 +3851,18 @@ internal ListLLC GetClone()
 
 				return clone;
 			}
+
+			//internal void FixWeirdMeasures()
+			//{
+			//	foreach (LaserLifeCounter LLC in this)
+			//		LLC.FixWeirdMeasures();
+			//}
 		}
 
 		static ListLLC mLLCL;
 		static LaserLifeCounter mCurrentLLC;
-		private static long mLastStatusHiResTimeNano;
-		private static long mLastPowerHiResTimeNano;
+		private static long? mLastStatusHiResTimeNano;
+		private static long? mLastPowerHiResTimeNano;
 		private static long mLastSave;
 		private static string mLLCFileName;
 
@@ -3946,7 +3952,7 @@ internal void AddTrueLaserTimePower(TimeSpan elapsed, double powerperc)
 					clx = Math.Min(9, Math.Max(0, clx)); //ensure 0-9 range
 					mTimeClasses[clx] = mTimeClasses[clx] + elapsed;
 				}
-
+				mLastUsage = DateTime.Today;
 				//System.Diagnostics.Debug.WriteLine($"LT: {mTimeInRun.TotalSeconds} LTT: {mTimeUsageNormalizedPower.TotalSeconds}");
 			}
 
@@ -3970,6 +3976,22 @@ void IDeserializationCallback.OnDeserialization(object sender)
 				if (mTimeClasses == null)
 					mTimeClasses = new TimeSpan[10];
 			}
+
+			//internal void FixWeirdMeasures()
+			//{
+			//	TimeSpan TT = TimeSpan.Zero;
+			//	foreach (TimeSpan TS in Classes)
+			//		TT = TT.Add(TS);
+
+			//	if (
+			//		LastUsage.HasValue &&
+			//		DateTime.Today < new DateTime(2023, 12, 31) && // smette di farlo ad una certa data
+			//		TimeInRun.TotalHours > 100 && // almeno 100 ore
+			//		TimeInRun.TotalHours > ((LastUsage.Value - MonitoringDate.Value).TotalHours + 24) * 2 && //TIR > 2 * DELTA TRA DATE MONITORATE
+			//		TimeInRun.TotalHours > TT.TotalHours * 100 //TIR > 100 volte Classes.Time
+			//		)
+			//		mTimeInRun = TimeSpan.FromHours(TT.TotalHours * 1.5); //ri-assegna da TT (total time preso dalle classi) esteso * 1.5
+			//}
 		}
 
 		static LaserLifeHandler()
@@ -3982,6 +4004,8 @@ static LaserLifeHandler()
 
 				if (mLLCL == null) mLLCL = new ListLLC();
 				if (mLLCL.Count == 0) mLLCL.Add(LaserLifeCounter.CreateDefault());
+
+				//mLLCL.FixWeirdMeasures();
 			}
 		}
 
@@ -3992,13 +4016,15 @@ public static void ComputeLaserTime(GrblCore.MacStatus status)
 				lock (mLLCL)
 				{
 					long now = HiResTimer.TotalNano;
-					if (mLastStatusHiResTimeNano != 0)
+					if (mLastStatusHiResTimeNano != null)
 					{
-						double delta = now - mLastPowerHiResTimeNano;
-						double perc = status == MacStatus.Run ? 1 : 0; //potenza da applicare a questo delta
-						double normal = delta * perc;
-
-						mCurrentLLC?.AddRunTime(TimeSpan.FromMilliseconds(normal / 1000 / 1000));
+						long delta = now - mLastPowerHiResTimeNano.Value;
+						if (delta > 0 && delta < 600000000000L) //do not add delta if bigger then 600s (or negative) - just a safety test
+						{ 
+							double perc = status == MacStatus.Run ? 1 : 0; //potenza da applicare a questo delta
+							double normal = delta * perc;
+							mCurrentLLC?.AddRunTime(TimeSpan.FromMilliseconds(normal / 1000 / 1000));
+						}
 					}
 					mLastStatusHiResTimeNano = now;
 				}
@@ -4020,15 +4046,18 @@ public static void ComputeLaserTrueTime(float power)
 				lock (mLLCL)
 				{
 					long now = HiResTimer.TotalNano;
-					if (mLastPowerHiResTimeNano != 0)
+					if (mLastPowerHiResTimeNano != null)
 					{
-						double elapsed = now - mLastPowerHiResTimeNano;
-						decimal maxpwm = Configuration.MaxPWM;
+						long delta = now - mLastPowerHiResTimeNano.Value;
+						if (delta > 0 && delta < 600000000000L) //do not add delta if bigger then 600s (or negative) - just a safety test
+						{ 
+							decimal maxpwm = Configuration.MaxPWM;
 
-						if (maxpwm >= 10 && maxpwm <= 100000) //we have a configured value in a valid range
-						{
-							double powerperc = Math.Max(0, Math.Min(1, (double)power / (double)maxpwm)); //potenza da applicare a questo delta
-							mCurrentLLC?.AddTrueLaserTimePower(TimeSpan.FromMilliseconds(elapsed / 1000 / 1000), powerperc);
+							if (maxpwm >= 10 && maxpwm <= 100000) //we have a configured value in a valid range
+							{
+								double powerperc = Math.Max(0, Math.Min(1, (double)power / (double)maxpwm)); //potenza da applicare a questo delta
+								mCurrentLLC?.AddTrueLaserTimePower(TimeSpan.FromMilliseconds((double)delta / 1000000.0), powerperc);
+							}
 						}
 					}
 					mLastPowerHiResTimeNano = now;
diff --git a/LaserGRBL/MainForm.cs b/LaserGRBL/MainForm.cs
index 878c4f87..88b776e0 100644
--- a/LaserGRBL/MainForm.cs
+++ b/LaserGRBL/MainForm.cs
@@ -294,6 +294,7 @@ void MainFormFormClosing(object sender, FormClosingEventArgs e)
 
 		private void UpdateTimer_Tick(object sender, EventArgs e)
 		{
+			long foo = HiResTimer.TotalNano; //ensure call TotalNano to be able to detect and fix sleep/hibernation
 			TimerUpdate();
 			ConnectionForm.TimerUpdate();
 			PreviewForm.TimerUpdate();
diff --git a/LaserGRBL/Tools/HiResTimer.cs b/LaserGRBL/Tools/HiResTimer.cs
index 461cbc9d..3f5f8a5d 100644
--- a/LaserGRBL/Tools/HiResTimer.cs
+++ b/LaserGRBL/Tools/HiResTimer.cs
@@ -215,11 +215,15 @@ public static long TotalNano
 						ComputeFrequency(now);
 
 					TimeReference delta = now.Subtract(mLastReference);
+					long deltaNano = delta.IsGoodHiRes() ? delta.HiResNano : delta.LowResNano;
+					long nanoSleepThreshold = 10000000000L; // se passano più di 10s tra due chiamate abbiamo avuto una sleep da non conteggiare! (assicurati di chiamare TotalNano con una frequenza più alta)
 
-					if (delta.IsGoodHiRes())
-						mTotalNano = mTotalNano + Math.Max(0, delta.HiResNano);
+					if (deltaNano < 0)
+						LaserGRBL.Logger.LogMessage("Issue detector", "Negative delta detected!");
+					else if (deltaNano > nanoSleepThreshold)
+						LaserGRBL.Logger.LogMessage("Issue detector", "System sleep/hibernation detected ({0}s)", deltaNano / 1000000000L);
 					else
-						mTotalNano = mTotalNano + Math.Max(0, delta.LowResNano);
+						mTotalNano += deltaNano;
 
 					mLastReference = now;
 
diff --git a/setup.iss b/setup.iss
index 24961d08..13ab12b9 100644
--- a/setup.iss
+++ b/setup.iss
@@ -2,7 +2,7 @@
 ; SEE THE DOCUMENTATION FOR DETAILS ON CREATING INNO SETUP SCRIPT FILES!
 
 #define MyAppName "LaserGRBL"
-#define MyAppVersion "5.4.0"
+#define MyAppVersion "5.5.0"
 #define MyAppVersionName "Rhydon"
 #define MyAppPublisher "LaserGRBL"
 #define MyAppURL "https://lasergrbl.com"