Hm, i understand (i see my mistake, sorry). The problem is, without " and with IE i can attached images, but with a click on that attached image, it shows me a wrong image. Will look later again. Thank you very much.
Edit:
I can constantly reprocedure it with IE 7. With Firefox no entries are written to the log.

The page/thread with the images need to refresh/reload to reproduce the error.
I have the plug-in disabled and edited the template directly, so i have no problems to display wrong images.
Regards, Stoebi