Date Initially Written: 21 March 2003.
Problem: When using the browse facility in Paint Shop Pro, all thumbnails are rebuilt from scratch.
Operating System: Windows 2000 Professional with service pack 3.
Background: Paint Shop Pro has a browse facility that scans a folder for graphic files and shows all the files it finds in a thumbnail format. The user has the option to save the thumbnails so that future browsing of the folder results in a quick display of the thumbnails (i.e. PSP doesn't need to re-read all the graphic files to build the thumbnails). The thumbnails are stored in a file called "pspbrwse.jbf", each browsed folder will contain one of these files.
This system works really well, until the other day I noticed that whenever I browsed a folder PSP was rebuilding the thumbnails. Rebuilding takes much longer than just reading the pspbrwse.jbf file, so this will be a real pain to anybody that has thousands of graphic files. I had never noticed PSP doing this before, normally it only re-reads graphic files that have changed since it last looked. I investigated further and found out why this was happening: daylight savings.
Resolution Steps: Actually there is no resolution, but at least I can explain why this happens. This behaviour occurs because of the way that Windows NT (and hence Windows 2000 and XP) stores a files' timestamp information. All timestamp's for files on an NTFS partition are stored using Greenwich Mean Time (GMT) and converted to the local time when they need to be used. This can cause some problems for programs that store timestamps in a database and then want to compare those timestamps with the timestamps on the files (this is exactly how PSP determines if a graphic file has changed and needs to be re-read to create a new thumbnail when using the Browse facility).
A search of Google Groups told me that plenty of other people have noticed this problem and are a bit ticked off by it. A couple of solutions were suggested, mainly along the lines of turning off the Automatic Daylight Savings Adjustment in Windows, but this isn't very satisfactory. A couple of interesting articles that go into this problem in a lot more detail:
I'd just like to repeat that this problem doesn't affect just Paint Shop Pro but also other programs too.
Recommended Reading For Solving Windows XP Problems: Microsoft Windows XP Inside Out, Second Edition