I have seen that in certain circumstances the Regional Settings actually only apply to the local user. Log into the QlikView Distribution Server in question with the account running the QDS service and then change the Regional Settings
The date appears with 0's because the QMS cannot understand the date format in the tasklog.txt file produced by the QDS. This can be confirmed by changing the logging in the QMC to DEBUG. When I did this I saw the following error:
System.Collections.Generic.List`1[[SolutionGlobal.Logging.LogfileEntry, SolutionGlobal, Version=11.20.12589.0, Culture=neutral, PublicKeyToken=null]]. String was not recognized as a valid DateTime. ---> System.FormatException: String was not recognized as a valid DateTime.
The QDS writes the date and timestamp to the tasklog based on its Regional Settings. Once the Regional Settings matched that of the QMS, we restarted the QDS and QMS services. Tasks dates and times were readable from then on.