Friends of InterAkt Extensions

Slowly I have migrated most development out of Kollection/ADDT & KTML, but I have a few sites still in service.
I have just come across an odd problem. I can't tell exactly when it started, but had to be over the past 6 months or so.

On sites hosted on IIS 6 (using PHP, not ASP) the KTML file editor no longer shows any thumbnails.
Images are uploaded fine, and I can insert them (and they show).

The folder(s) that KTML upload to all have permissions set to allow the file upload, and I have even set "IUSR_<servename>" to FULL ACCESS for testing, and that did not help.

When I copy this entire site over to an IIS7 server, or an Apache server it all works fine, and thumbnails are shown.
It is almost as if the GD installation has gone bad - but it works with a normal file upload.

Any ideas why I can't get this to work in IIS6? Any additional folders I may need to apply permissions to?
Any suggestions would be appreciated.

No idea as I never used ISS servers.
Any indications in the server logs or the error_log in the folder from where the script is called?

Good call Fred. The logs are showing a Access Denial so it is defintely a security setting somewhere.
Time to go over my changes over the past few months and see if I did anything - otherwise it might be one of those goofy Windows Updates locking things down without warning.

Thanks for the suggestion! Not sure why I didn't think of the logs.

SOLVED - It turns out I had installed an IIS "add-on" called URLSCAN, which is used to try and block malicious access to a server via the URL.
One of the default settings is to not allow anything with a "dot" in the path - unless it is a file extension. KTML uses ".thumbnails" to store all of its thumbs, so of course, none of these were displaying.

It also explains why my "captcha" images stopped worked a couple months back - LOL! I couldn't figure that one out and re-wrote all the Captcha scripts to go to a different path. Now I realize exactly what was causing it. All this time I've been blaming Microsoft for a faulty update, all along it was me who simply tried to tighten security a little

Thanks again Fred for directing me to the log files. Issue is now solved.

Sounds familiar,
One of my clients tried to install phpbb using fantastico from his cpanel the other day.
It copied the files but simply would not create the DB.

Turned out a mod_sec rule was stopping him. Took me a couple of hours to figure that one out as well.