Starting this month, our Internet Web Application suddenly showed some back dated year on some date column. A complain from the data entry operator of computer hang up and slowness has been logged. This all coincided with the Conficker computer worm known date of wreaking havoc.

We’ve pulled out the desktop computer and scanned it with Microsoft Malicious Software Removal Tool. Antivirus software like ESET NOD32 and TrendMicro were used to scan and clean the computer. There were several VB script viruses, Malware, and worm identified and quarantined.

The computer was deployed back for use after antivirus scanning. The problem seemed to persist though. The entered data through the Microsoft Access Form was back dated by 543 years. This is consistent with all data entered through this client computer. A strange behavior for the application software, but could not be attributed to computer virus.

We’ve learned from further investigation that the Windows XP system and MS Access was set to use Thai Calendar setting which caused the date entries to be back dated 543 years. Entering standard year of 2009 in a Thai Calendar set computer would save the year as 1466 in an English Calendar based computer server.

This have caused confusion, but it was now clear that if a computer system is set to use say Thai Calendar then Thai date should also be used to avoid error. We’re thankful that the 543 years back dated date entries were not after all caused by the feared Conficker computer virus.