Solved. The issue was caused by automatic adjustment of the clock for daylight saving time. I only wish to warn a captious user that while in this mode it's not always safe to work with certain files, as their timestamps may eventually "stick" due to some odd misunderstanding on the part of windows explorer and/or archivers. So be on guard.

Here's the thing. I'm not sure if you guys know it, but i've noticed something really strange happening to unarchived files after a certain period of time. Yes, exactly that, their timestamps change, specifically the hour part (it shows +1:00). At first they are only displayed wrong, whereas in archives (WinRAR) the correct time is shown. However, if kept unarchived for a certain period of time the timestamps may change forever to what previously was only displayed wrongly. So basically, they are somehow oddly and randomly redefined by the system. I know this has been going on for a while, i've simply never noticed it before. I know the archives show the correct time, cause it's the same in DOSBox and Vbox (WinXP), but Win 7 explorer and Total Commander seem to show identical results. Also, i noticed that not all files show an altered timestamps, some keep old ones. Any ideas?