This is a common problem and stems from a misconception. I'm assuming that you server's clock is set to automatically adjust for daylight saving time. There is a serious problem with this when time jumps backward in the Autumn. Powerlog use date/time encoded filenames to make navigating the log folders easy. However, what happens is that it will record the 01:00 - 01:59 hour and then the clock will jump back to 01:00 again. It will then proceed to overwrite the 01:00 BST hour with the 01:00 GMT hour.
The solution is run the server on GMT. Since GMT time is flat there is no problem with jumping of any sort. The times displayed on the client are adjusted for you based on a set of rules which can be found in the Settings menu of the client. These rules default to British standards. Note that some older versions had an incorrect default setting for the fallback point (September, not October) so check that they are correct.
Now, the only potential spanner in the works is Tardis. If it sets the clock to the 'current' time and ignores DST settings then it could cause trouble by setting your GMT server to BST times. I'm not too familiar with it so I can't say for sure.
Am I right in saying that if you are using K9 then the Powerlog Server is drawing its time from another machine of the LAN running Tardis?
If so then if you have problems with it setting the server clock to the current BST time then lose K9 entirely and use Windows' built in time sync service
. Since this is a comms protocol between two LAN PCs it does not matter that you will be using Tardis instead of a radion clock at the time server.